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NCERT Formula Library

Formula Library

Real NCERT formulas linked directly to their chapter — every entry opens the same verified page students see while learning that chapter.

Mathematics

272 formulas
Time
Class 1
Days in a Week
1 week = 7 days
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
Time
Class 1
Months in a Year
1 year = 12 months = 365 days (or 366 in a leap year)
January to December
Numbers from Ten to Twenty
Class 1
Teen Numbers
10 + ones digit = teen number
Numbers 11-19 are called "teen" numbers
Numbers from Ten to Twenty
Class 1
Place Value
Any 2-digit number = (tens × 10) + ones
13 = (1×10) + 3 = 10+3 = 13
Subtraction
Class 1
Subtraction
Whole - Part = Remaining Part
You cannot subtract a bigger number from a smaller number in Class 1
Subtraction
Class 1
Subtraction Fact
If a + b = c, then c - b = a
Since 3+4=7, we know 7-4=3 and 7-3=4
Numbers from One to Nine
Class 1
Counting Rule
Count each object once and only once
Always count from left to right or top to bottom to avoid missing any
Addition
Class 1
Addition
Part + Part = Whole
The order does not matter: 3+4 = 4+3 = 7
Addition
Class 1
Adding Zero
Any number + 0 = that number
Zero is the identity for addition
Money
Class 1
Change Calculation
Change = Amount Given - Cost
Cost ₹7, gave ₹10, change = ₹10 - ₹7 = ₹3
Money
Class 1
Paise to Rupees
100 paise = ₹1
250 paise = ₹2 and 50 paise
Real Numbers
Class 10
Euclid Division Lemma
a = bq + r, 0 ≤ r < b
Used repeatedly to find HCF.
Real Numbers
Class 10
HCF-LCM Relationship
HCF(a, b) × LCM(a, b) = a × b
For 12 and 18: 6 × 36 = 12 × 18 = 216
Real Numbers
Class 10
Terminating Decimal Test
If q = 2^m × 5^n in lowest form, then p/q terminates
3/40 terminates because 40 = 2^3 × 5
Polynomials
Class 10
Sum of Zeroes
α + β = -b/a
For x² - 5x + 6, sum of zeroes = 5
Polynomials
Class 10
Product of Zeroes
αβ = c/a
For x² - 5x + 6, product of zeroes = 6
Polynomials
Class 10
Cubic Relation
α + β + γ = -b/a
For ax³ + bx² + cx + d, sum of zeroes depends on coefficient of x²
Pair of Linear Equations in Two Variables
Class 10
Unique Solution Condition
a₁/a₂ ≠ b₁/b₂
If ratios of x and y coefficients differ, the lines intersect once
Pair of Linear Equations in Two Variables
Class 10
Infinite Solutions Condition
a₁/a₂ = b₁/b₂ = c₁/c₂
Both equations represent the same line
Pair of Linear Equations in Two Variables
Class 10
No Solution Condition
a₁/a₂ = b₁/b₂ ≠ c₁/c₂
Both lines are parallel and distinct
Quadratic Equations
Class 10
Standard Form
ax² + bx + c = 0, a ≠ 0
2x² - 7x + 3 = 0 is in standard form
Quadratic Equations
Class 10
Quadratic Formula
x = [-b ± √(b² - 4ac)] / 2a
For x² - 5x + 6 = 0, roots are 2 and 3
Quadratic Equations
Class 10
Discriminant
D = b² - 4ac
For x² + 2x + 1, D = 0 so the roots are equal
Arithmetic Progressions
Class 10
nth Term
aₙ = a + (n - 1)d
If a = 3 and d = 4, then a₅ = 3 + 4×4 = 19
Arithmetic Progressions
Class 10
Sum of First n Terms
Sₙ = n/2 [2a + (n - 1)d]
For a = 2, d = 3, n = 4: S₄ = 4/2[4 + 9] = 26
Arithmetic Progressions
Class 10
Sum Using Last Term
Sₙ = n/2 (a + l)
If first term is 5, last term is 25 and n = 5, sum = 75
Triangles
Class 10
Area Ratio of Similar Triangles
Ar(ΔABC) / Ar(ΔPQR) = (AB / PQ)²
If corresponding sides are in ratio 2:3, areas are in ratio 4:9
Triangles
Class 10
Pythagoras Theorem
a² + b² = c²
For sides 3, 4, 5: 3² + 4² = 5²
Triangles
Class 10
Basic Proportionality Idea
If a line is parallel to one side of a triangle, it divides the other two sides proportionally
Useful in many textbook proofs
Coordinate Geometry
Class 10
Distance Formula
d = √[(x₂ - x₁)² + (y₂ - y₁)²]
Distance between (1,2) and (4,6) is 5
Coordinate Geometry
Class 10
Midpoint Formula
M = ((x₁ + x₂)/2, (y₁ + y₂)/2)
Midpoint of (2,4) and (6,8) is (4,6)
Coordinate Geometry
Class 10
Internal Section Formula
P = ((mx₂ + nx₁)/(m+n), (my₂ + ny₁)/(m+n))
Used when one point divides a segment in m:n
Introduction to Trigonometry
Class 10
Basic Ratios
sin θ = P/H, cos θ = B/H, tan θ = P/B
In a 3-4-5 triangle with angle opposite 3, sin θ = 3/5
Introduction to Trigonometry
Class 10
Identity
sin²θ + cos²θ = 1
If sin θ = 3/5, then cos θ = 4/5
Introduction to Trigonometry
Class 10
Derived Identity
1 + tan²θ = sec²θ
If tan θ = 3/4, then sec²θ = 25/16
Some Applications of Trigonometry
Class 10
Angle of Elevation Model
tan θ = height / horizontal distance
If θ = 45° and distance = 20 m, height = 20 m
Some Applications of Trigonometry
Class 10
Angle of Depression Link
Angle of depression from the top equals the corresponding angle of elevation from below
This equality helps convert many observation problems
Circles
Class 10
Radius-Tangent Property
Radius at the point of contact ⟂ tangent
If PT is tangent at T and OT is radius, then OT ⟂ PT
Circles
Class 10
Equal Tangent Lengths
PA = PB
If tangents from P touch the circle at A and B, then PA = PB
Areas Related to Circles
Class 10
Area of Circle
A = πr²
If r = 7 cm, area = 49π cm²
Areas Related to Circles
Class 10
Circumference
C = 2πr
If r = 7 cm, circumference = 14π cm
Areas Related to Circles
Class 10
Area of Sector
Area = (θ/360) × πr²
If θ = 90° and r = 14 cm, area = 49π cm²
Surface Areas and Volumes
Class 10
Volume of Cylinder
V = πr²h
For r = 3 cm, h = 10 cm, volume = 90π cm³
Surface Areas and Volumes
Class 10
Volume of Sphere
V = 4/3 πr³
For r = 3 cm, volume = 36π cm³
Surface Areas and Volumes
Class 10
TSA of Cylinder
TSA = 2πr(h + r)
For r = 2 cm and h = 5 cm, TSA = 28π cm²
Statistics
Class 10
Mean
Mean = Σfx / Σf
Multiply each class mark by frequency and divide by total frequency
Statistics
Class 10
Mode
Mode = l + [(f₁ - f₀) / (2f₁ - f₀ - f₂)] × h
Use the modal class and neighbouring frequencies
Statistics
Class 10
Median
Median = l + [(N/2 - cf) / f] × h
Find the median class using cumulative frequency first
Probability
Class 10
Basic Probability
P(E) = n(E) / n(S)
If 3 outcomes are favourable out of 8 total, probability = 3/8
Probability
Class 10
Complement Rule
P(E) + P(not E) = 1
If P(E) = 0.35, then P(not E) = 0.65
Binomial Theorem
Class 11
(a+b)ⁿ = Σ ⁿCr aⁿ⁻ʳ bʳ
(a+b)ⁿ = Σ ⁿCr aⁿ⁻ʳ bʳ
Complex Numbers and Quadratic Equations
Class 11
i² = -1
i² = -1
Complex Numbers and Quadratic Equations
Class 11
|z| = √(a²+b²)
|z| = √(a²+b²)
Complex Numbers and Quadratic Equations
Class 11
Quadratic formula
Quadratic formula
Conic Sections
Class 11
Circle: x²+y²=r²
Circle: x²+y²=r²
Conic Sections
Class 11
Parabola: y²=4ax
Parabola: y²=4ax
Conic Sections
Class 11
Ellipse: x²/a²+y²/b²=1
Ellipse: x²/a²+y²/b²=1
Limits and Derivatives
Class 11
d/dx(xⁿ) = nxⁿ⁻¹
d/dx(xⁿ) = nxⁿ⁻¹
Limits and Derivatives
Class 11
d/dx(sin x) = cos x
d/dx(sin x) = cos x
Limits and Derivatives
Class 11
d/dx(eˣ) = eˣ
d/dx(eˣ) = eˣ
Permutations and Combinations
Class 11
ⁿPr = n!/(n-r)!
ⁿPr = n!/(n-r)!
Permutations and Combinations
Class 11
ⁿCr = n!/r!(n-r)!
ⁿCr = n!/r!(n-r)!
Sequences and Series
Class 11
Sum of AP = n/2(2a+(n-1)d)
Sum of AP = n/2(2a+(n-1)d)
Sequences and Series
Class 11
Sum of GP = a(rⁿ-1)/(r-1)
Sum of GP = a(rⁿ-1)/(r-1)
Trigonometric Functions
Class 11
Fundamental Identity
sin²θ + cos²θ = 1
Most important — used in almost every problem
Trigonometric Functions
Class 11
Sum Formulas
sin(A+B) = sinAcosB + cosAsinB cos(A+B) = cosAcosB - sinAsinB
sin75° = sin(45°+30°) = (1/√2)(√3/2)+(1/√2)(1/2) = (√3+1)/(2√2)
Trigonometric Functions
Class 11
Double Angle
sin2A = 2sinAcosA cos2A = cos²A - sin²A = 1-2sin²A
sin60°=sin(2×30°)=2×sin30°×cos30°=2×(1/2)×(√3/2)=√3/2 ✓
Trigonometric Functions
Class 11
Product to Sum
2sinAcosB = sin(A+B) + sin(A-B)
2sin75°cos15° = sin90°+sin60° = 1+√3/2
Application of Derivatives
Class 12
Slope of Tangent
m = dy/dx|_(x₁,y₁) = f'(x₁)
y=x³-2x at (1,-1): m=3x²-2|_{x=1}=3-2=1. Tangent: y+1=1(x-1)→y=x-2
Application of Derivatives
Class 12
Equation of Normal
y - y₁ = (-1/m)(x - x₁) where m = f'(x₁)
At (1,-1) with m=1: Normal: y+1=-1(x-1)→y=-x
Application of Derivatives
Class 12
2nd Derivative Test
f'(x₀)=0 AND f''(x₀)<0 → local max | f''(x₀)>0 → local min
f(x)=x²-4x+3: f'=2x-4=0→x=2. f''=2>0 → local min at x=2, f(2)=-1
Application of Derivatives
Class 12
Related Rates
Use chain rule: dV/dt = dV/dr × dr/dt
Sphere: V=4πr³/3 → dV/dt=4πr²×dr/dt. Given dr/dt=2cm/s at r=5: dV/dt=4π×25×2=200π cm³/s
Determinants
Class 12
|A| = a(ei-fh) - b(di-fg) + c(dh-eg)
|A| = a(ei-fh) - b(di-fg) + c(dh-eg)
Determinants
Class 12
A⁻¹ = adj(A)/|A|
A⁻¹ = adj(A)/|A|
Differential Equations
Class 12
dy/dx = f(x)g(y)
dy/dx = f(x)g(y)
Differential Equations
Class 12
dy/dx + Py = Q
dy/dx + Py = Q
Integrals
Class 12
∫xⁿdx = xⁿ⁺¹/(n+1)
∫xⁿdx = xⁿ⁺¹/(n+1)
Integrals
Class 12
∫sin x dx = -cos x
∫sin x dx = -cos x
Integrals
Class 12
∫eˣdx = eˣ
∫eˣdx = eˣ
Inverse Trigonometric Functions
Class 12
sin⁻¹(-x) = -sin⁻¹x
sin⁻¹(-x) = -sin⁻¹x
Inverse Trigonometric Functions
Class 12
sin⁻¹x + cos⁻¹x = π/2
sin⁻¹x + cos⁻¹x = π/2
Matrices
Class 12
(AB)T = BTAT
(AB)T = BTAT
Matrices
Class 12
(A+B)T = AT+BT
(A+B)T = AT+BT
Probability
Class 12
Conditional Probability
P(A|B) = P(A∩B) / P(B)
P(A∩B)=0.12, P(B)=0.4: P(A|B)=0.12/0.4=0.3
Probability
Class 12
Bayes' Theorem
P(Aᵢ|B) = P(Aᵢ)P(B|Aᵢ) / Σ P(Aⱼ)P(B|Aⱼ)
Classic problem: factory machines producing defective items
Probability
Class 12
Binomial Distribution
P(X=r) = ⁿCᵣ pʳ qⁿ⁻ʳ | Mean=np | Variance=npq
Coin tossed 5 times: P(3 heads)=⁵C₃×(1/2)³×(1/2)²=10/32=5/16
Probability
Class 12
Total Probability
P(B) = Σᵢ P(B|Aᵢ)×P(Aᵢ)
Used when event B can happen via multiple paths A₁, A₂, A₃...
Three Dimensional Geometry
Class 12
l²+m²+n² = 1
l²+m²+n² = 1
Three Dimensional Geometry
Class 12
Distance of point from plane
Distance of point from plane
Vector Algebra
Class 12
a·b = |a||b|cosθ
a·b = |a||b|cosθ
Vector Algebra
Class 12
|a×b| = |a||b|sinθ
|a×b| = |a||b|sinθ
Counting in Groups
Class 2
Multiplication as Repeated Addition
a × b = a + a + a... (b times)
Or: 3×5 = 3+3+3+3+3 = 15 (three added five times). Both give 15!
Counting in Groups
Class 2
Commutative Property
a × b = b × a
4 × 6 = 6 × 4 = 24
What is Long, What is Round?
Class 2
Shape Properties Summary
Cube: 6 faces, 12 edges, 8 vertices | Cuboid: 6 faces, 12 edges, 8 vertices | Cone: 2 faces, 1 edge, 1 vertex | Cylinder: 3 faces, 2 edges, 0 vertices
A die is a cube — count: 6 faces (each face has numbers 1-6), 12 edges, 8 corners
Jugs and Mugs
Class 2
Capacity Units
1 litre (L) = 1000 millilitres (mL)
Large amounts use kilolitres (kL): 1 kL = 1000 L
Counting in Tens
Class 2
Expanded Form
2-digit number = Tens digit × 10 + Ones digit × 1
This is called expanded notation
Counting in Tens
Class 2
Place Value
Place value = Face value × Position value
In 73: place value of 7 = 7×10 = 70; place value of 3 = 3×1 = 3
Tens and Hundreds
Class 2
Expanded Form (3-digit)
3-digit number = H×100 + T×10 + O×1
H=hundreds digit, T=tens digit, O=ones digit
Tens and Hundreds
Class 2
Hundreds
10 tens = 1 hundred
10 groups of 10 = 100
How Much Can You Carry?
Class 2
Standard Weight Units
1 kg = 1000 g
kg = kilogram, g = gram
Give and Take
Class 2
Column Subtraction
Subtract ones first, then tens (borrow if top < bottom)
54-28: ones=4<8 so borrow; 14-8=6; tens=(5-1)-2=2; answer=26
Give and Take
Class 2
Checking Subtraction
Answer + Subtracted number = Original number
54-28=26; check: 26+28=54 ✓
Add Our Points
Class 2
Column Addition
Add ones first, then tens (carry if sum ≥ 10)
47+35: ones=7+5=12(write 2,carry 1); tens=4+3+1=8; answer=82
Footprints
Class 2
Unit Conversion
1 m = 100 cm
km = kilometre: 1 km = 1000 m (for long distances like roads)
Long and Short
Class 3
Unit conversion
10 mm = 1 cm | 100 cm = 1 m | 1000 m = 1 km
Convert from larger to smaller unit: multiply. Smaller to larger: divide.
Long and Short
Class 3
Perimeter of Rectangle
P = 2 × (length + breadth)
Rectangle 8 cm × 5 cm: P = 2×(8+5) = 2×13 = 26 cm
Long and Short
Class 3
Perimeter of Square
P = 4 × side
Square side = 7 cm: P = 4×7 = 28 cm
Fun with Numbers
Class 3
Expanded Form (4-digit)
Th×1000 + H×100 + T×10 + O×1
Th=thousands, H=hundreds, T=tens, O=ones
Give and Take
Class 3
Column Addition
Add ones first, then tens, then hundreds
Carry means a group of 10 is moved to the next higher place value
Give and Take
Class 3
Column Subtraction
Subtract ones first, then tens, then hundreds
503 - 248 = 255 (3<8: borrow; 13-8=5; 0-1-4: borrow; 10-5=5; 5-1-2=2)
Who is Heavier?
Class 3
Weight Units
1 kg = 1000 g
Scientific unit of mass is kilogram (kg)
How Many Times?
Class 3
Multiplication
a × b = a added b times
Also: 6×4 = 4×6 = 24 (commutative)
How Many Times?
Class 3
Multiply by 0
Any number × 0 = 0
999 × 0 = 0
How Many Times?
Class 3
Multiply by 1
Any number × 1 = that number
45 × 1 = 45
Time Goes On
Class 3
Time Conversion
60 seconds = 1 minute | 60 minutes = 1 hour | 24 hours = 1 day | 7 days = 1 week | 52 weeks = 1 year
2 hours = 2×60 = 120 minutes | 3 days = 3×24 = 72 hours
Can We Share?
Class 3
Division
Dividend ÷ Divisor = Quotient
24 ÷ 6 = 4 (24 is dividend, 6 is divisor, 4 is quotient)
Can We Share?
Class 3
Division-Multiplication Relationship
If a ÷ b = c, then b × c = a
If 15 ÷ 3 = 5, then 3 × 5 = 15
Can We Share?
Class 3
Division by 1
Any number ÷ 1 = same number
67 ÷ 1 = 67
Fields and Fences
Class 4
Perimeter of Rectangle
P = 2 × (l + b)
l=length, b=breadth
Fields and Fences
Class 4
Perimeter of Square
P = 4 × s
s=side length
Fields and Fences
Class 4
Area of Rectangle
A = l × b
Rectangle 8m × 5m: A = 8×5 = 40 sq m
Fields and Fences
Class 4
Area of Square
A = s × s = s²
Square with side 6cm: A = 6×6 = 36 sq cm
Building with Bricks
Class 4
Multiplication
Multiplicand × Multiplier = Product
23 × 14 = 322 (23 is multiplicand, 14 is multiplier, 322 is product)
Building with Bricks
Class 4
Multiply by Powers of 10
N × 10 = N with one extra 0 | N × 100 = N with two extra 0s
56 × 1000 = 56,000
Halves and Quarters
Class 4
Fraction
Fraction = Numerator / Denominator
In 3/8: numerator=3, denominator=8, meaning 3 parts out of 8 equal parts
Halves and Quarters
Class 4
Finding Fraction of a Number
p/q of N = N ÷ q × p
3/4 of 20 = 20÷4×3 = 5×3 = 15
Tick Tick Tick
Class 4
24-hour conversion
PM time (except noon): 24-hr = 12-hr + 12
3:00 PM = 3+12 = 15:00 | 8:30 PM = 8:30+12 = 20:30
Tick Tick Tick
Class 4
Time difference
End time - Start time = Duration
15:45 - 11:20 = 4 h 25 min
A Trip to Bhopal
Class 4
Map Scale
Actual distance = Map distance × Scale factor
Map distance 5 cm, scale 1 cm = 50 km → Actual = 5×50 = 250 km
Shapes and Angles
Class 5
Angle Sum of Triangle
∠A + ∠B + ∠C = 180°
If two angles are 60° and 70°, third angle = 180-60-70 = 50°
Shapes and Angles
Class 5
Angle Sum of Quadrilateral
Sum of all 4 angles = 360°
If three angles are 90°, 90°, 80°, fourth angle = 360-260 = 100°
Shapes and Angles
Class 5
Area of Rectangle
Area = length × breadth
Room 5m × 4m: Area = 5×4 = 20 m²
Shapes and Angles
Class 5
Area of Square
Area = side × side = side²
Square with side 6 cm: Area = 6² = 36 cm²
How Many Squares?
Class 5
Area of Rectangle
A = l × b
Area unit is always "squared" (cm², m², km²)
How Many Squares?
Class 5
Area of Square
A = s²
7 cm × 7 cm = 49 cm²
Parts and Wholes
Class 5
Equivalent Fractions
a/b = (a×n)/(b×n) for any non-zero n
3/4 = 6/8 = 9/12 (multiply by 2, then 3)
Parts and Wholes
Class 5
Adding Fractions (same denom)
a/c + b/c = (a+b)/c
3/7 + 2/7 = 5/7
Parts and Wholes
Class 5
Adding Fractions (different denom)
a/b + c/d = (a×d + c×b)/(b×d)
1/3 + 1/4 = (4+3)/12 = 7/12
The Fish Tale
Class 5
Indian Number System
1 crore = 100 lakh | 1 lakh = 100 thousand | 1 thousand = 10 hundred
2,75,48,923 = 2 crore 75 lakh 48 thousand 9 hundred 23
The Fish Tale
Class 5
Rounding Rule
If digit to the right is ≥ 5: round up | < 5: round down
Round 7,349 to nearest hundred: look at tens digit (4 < 5) → 7,300
Be My Multiple, I'll be Your Factor
Class 5
HCF × LCM Relationship
HCF × LCM = Product of two numbers
For 12 and 18: HCF=6, LCM=36. Check: 6×36 = 216 = 12×18 ✓
Be My Multiple, I'll be Your Factor
Class 5
Finding HCF (Division Method)
Divide larger by smaller; replace larger with remainder; repeat till remainder = 0
HCF(18,12): 18÷12=1 R6; 12÷6=2 R0; HCF=6
Can You See the Pattern?
Class 5
Fibonacci Rule
F(n) = F(n-1) + F(n-2)
Starting values: F(1)=1, F(2)=1
Can You See the Pattern?
Class 5
Magic Sum Formula
Magic sum of n×n square using 1 to n² = n(n²+1)/2
3×3 square: 3×(9+1)/2 = 3×5 = 15
Mapping Your Way
Class 5
Speed-Distance-Time Triangle
S = D/T | D = S×T | T = D/S
Speed = 60 km/h, Time = 2.5 h → Distance = 60×2.5 = 150 km
Boxes and Sketches
Class 5
Volume of Cuboid
V = l × b × h
4 cm × 3 cm × 5 cm = 60 cm³
Boxes and Sketches
Class 5
Volume of Cube
V = s³
6 cm cube: V = 6³ = 216 cm³
Boxes and Sketches
Class 5
Surface Area of Cube
SA = 6s²
5 cm cube: SA = 6×25 = 150 cm²
Tenths and Hundredths
Class 5
Decimal to Fraction
Move denominator as power of 10 based on decimal places
0.7 = 7/10; 0.45 = 45/100; 0.125 = 125/1000
Tenths and Hundredths
Class 5
Comparing Decimals
Compare whole part first; if equal compare tenth; if equal compare hundredth
3.45 vs 3.52: whole equal; tenths 4<5; so 3.45 < 3.52
Area and its Boundary
Class 5
Area of Rectangle
A = l × b
l=length, b=breadth
Area and its Boundary
Class 5
Area of Square
A = s²
s=side
Area and its Boundary
Class 5
Perimeter of Rectangle
P = 2(l + b)
l=12cm, b=7cm: P=2×(12+7)=2×19=38 cm
Knowing Our Numbers
Class 6
Place Value
Place Value = Face Value × Position Value
Position values: 1, 10, 100, 1000...
Knowing Our Numbers
Class 6
Estimation (nearest 10)
If units ≥ 5: add 10, units=0. If units < 5: units=0
67 → 70, 54 → 50, 85 → 90
Knowing Our Numbers
Class 6
Large Number Formula
1 crore = 100 lakhs = 10 million
2.5 crore = 25 million = 25,000,000
Playing with Numbers
Class 6
HCF × LCM Relation
HCF(a,b) × LCM(a,b) = a × b
HCF(4,6)=2, LCM(4,6)=12. Check: 2×12=24=4×6 ✓
Playing with Numbers
Class 6
Divisibility by 3
Sum of all digits divisible by 3
783: 7+8+3=18, 18÷3=6. So 783 is divisible by 3 ✓
Playing with Numbers
Class 6
Divisibility by 9
Sum of all digits divisible by 9
5832: 5+8+3+2=18, 18÷9=2. So 5832 divisible by 9 ✓
Whole Numbers
Class 6
Commutative Property
a + b = b + a | a × b = b × a
7+3=3+7=10, 4×6=6×4=24
Whole Numbers
Class 6
Associative Property
(a+b)+c = a+(b+c) | (a×b)×c = a×(b×c)
(2+3)+4 = 2+(3+4) = 9
Whole Numbers
Class 6
Distributive Property
a × (b + c) = a×b + a×c
Most useful property for mental math
Understanding Elementary Shapes
Class 6
Complementary Angles
a + b = 90° (they complement each other)
Complement of 35° = 90-35 = 55°
Understanding Elementary Shapes
Class 6
Supplementary Angles
a + b = 180° (they supplement each other)
Supplement of 110° = 180-110 = 70°
Understanding Elementary Shapes
Class 6
Euler's Formula for 3D shapes
Faces + Vertices - Edges = 2
Cube: 6+8-12=2 ✓, Tetrahedron: 4+4-6=2 ✓
Basic Geometrical Ideas
Class 6
Sum of angles in triangle
∠A + ∠B + ∠C = 180°
If two angles are 60° and 70°, third angle = 180-60-70 = 50°
Basic Geometrical Ideas
Class 6
Sum of angles in quadrilateral
∠A + ∠B + ∠C + ∠D = 360°
If three angles are 90°, 90°, 100°: fourth = 360-280 = 80°
Basic Geometrical Ideas
Class 6
Diameter and Radius
d = 2r | r = d/2
r=5cm → d=10cm. d=14cm → r=7cm
Algebra
Class 6
Matchstick Pattern (triangles)
n triangles require (2n+1) matchsticks
4 triangles: 2×4+1 = 9 matchsticks
Algebra
Class 6
Perimeter using variable
Square with side l: Perimeter = 4l
l=5cm: P=4×5=20cm. l=x cm: P=4x cm
Decimals
Class 6
Decimal Place Values
...Hundreds | Tens | Ones . Tenths | Hundredths | Thousandths...
5.374: 5 = ones, 3 = tenths, 7 = hundredths, 4 = thousandths
Decimals
Class 6
Fraction to Decimal
Divide numerator by denominator
3/4 = 3÷4 = 0.75. 1/8 = 0.125. 1/3 = 0.333...
Decimals
Class 6
Money Conversion
₹1 = 100 paise. So ₹p.q means p rupees q paise
₹7.05 = 7 rupees 5 paise = 705 paise
Integers
Class 6
Additive Inverse
a + (-a) = 0, so additive inverse of a is -a
Additive inverse of 7 is -7. Of -12 is 12. Of 0 is 0.
Integers
Class 6
Integer Subtraction
a - b = a + (-b)
5 - (-3) = 5 + 3 = 8. (-4) - (-7) = (-4) + 7 = 3
Integers
Class 6
Sign Rules for Addition
+×+ = +, -×- = +, +×- = -, -×+ = -
(+7)×(+3)=+21, (-7)×(-3)=+21, (+7)×(-3)=-21
Data Handling
Class 6
Mean (Average)
Mean = Sum of all values / Number of values
Data: 12, 18, 15, 20, 10. Sum=75, n=5. Mean=75/5=15
Data Handling
Class 6
Tally Marks
Every 5th mark crosses previous 4 (like a gate)
HH HH HH | = 11 items
Fractions
Class 6
Equivalent Fractions
a/b = (a×n)/(b×n) for any n≠0
2/3 = 4/6 = 6/9 = 10/15
Fractions
Class 6
Converting Mixed to Improper
a(b/c) = (a×c + b)/c
2¾ = (2×4+3)/4 = 11/4
Fractions
Class 6
Adding Fractions (different denom)
a/b + c/d = (ad+bc)/bd
1/3 + 1/4 = (4+3)/12 = 7/12
Mensuration
Class 6
Perimeter of Rectangle
P = 2(l + b)
l=length, b=breadth
Mensuration
Class 6
Perimeter of Square
P = 4 × s
s=side length
Mensuration
Class 6
Area of Rectangle
A = l × b
l=8cm, b=5cm → A=8×5=40 cm²
Mensuration
Class 6
Area of Square
A = s × s = s²
Side=7cm → A=7²=49 cm²
Ratio and Proportion
Class 6
Ratio in simplest form
a:b = a/HCF(a,b) : b/HCF(a,b)
24:36 → HCF=12 → 2:3
Ratio and Proportion
Class 6
Proportion Test
a:b::c:d if and only if a×d = b×c
3:4::6:8 → 3×8=24, 4×6=24 ✓ In proportion
Symmetry
Class 6
Lines of symmetry
Regular polygon with n sides has n lines of symmetry
Equilateral triangle (n=3): 3 lines. Square (n=4): 4 lines. Regular hexagon (n=6): 6 lines
Lines and Angles
Class 7
Complementary angles: a + b = 90°
Complementary angles: a + b = 90°
Lines and Angles
Class 7
Supplementary angles: a + b = 180°
Supplementary angles: a + b = 180°
Lines and Angles
Class 7
Vertically opposite angles are equal
Vertically opposite angles are equal
Exponents and Powers
Class 7
aᵐ × aⁿ = aᵐ⁺ⁿ
aᵐ × aⁿ = aᵐ⁺ⁿ
Exponents and Powers
Class 7
aᵐ ÷ aⁿ = aᵐ⁻ⁿ
aᵐ ÷ aⁿ = aᵐ⁻ⁿ
Exponents and Powers
Class 7
(aᵐ)ⁿ = aᵐⁿ
(aᵐ)ⁿ = aᵐⁿ
Exponents and Powers
Class 7
a⁰ = 1
a⁰ = 1
Integers
Class 7
Sign Rules
(+)×(+)=+, (−)×(−)=+, (+)×(−)=−, (−)×(+)=-
(−5)×(+3)=−15, (−4)×(−7)=+28
Integers
Class 7
Absolute Value
|a| = a if a≥0, |a| = −a if a<0
|−8|=8, |+6|=6, |0|=0
Data Handling
Class 7
Mean
Mean = Sum of all observations / Total number
Data: 4,7,8,9,2. Sum=30, n=5. Mean=6
Data Handling
Class 7
Probability
P(event) = Number of favourable outcomes / Total outcomes
P(head) = 1/2. P(ace from deck) = 4/52 = 1/13
Perimeter and Area
Class 7
Area of Triangle
A = ½ × b × h
h is perpendicular height, not slant
Perimeter and Area
Class 7
Area of Parallelogram
A = b × h
b=8cm, h=5cm: A = 8×5 = 40 cm²
Perimeter and Area
Class 7
Circumference of Circle
C = 2πr = πd
r=7cm: C = 2×22/7×7 = 44 cm
Perimeter and Area
Class 7
Area of Circle
A = πr²
r=7cm: A = 22/7×49 = 154 cm²
Perimeter and Area
Class 7
Area of Semi-circle
A = πr²/2
r=7: A = 154/2 = 77 cm²
Fractions and Decimals
Class 7
Fraction multiplication
a/b × c/d = ac/bd
2/3 × 3/4 = 6/12 = 1/2
Fractions and Decimals
Class 7
Fraction division (reciprocal)
a/b ÷ c/d = a/b × d/c
2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6
Simple Equations
Class 7
Linear Equation
ax + b = c → x = (c - b) / a
a ≠ 0
Simple Equations
Class 7
Transposition Rule
If ax + b = c, then ax = c - b (b moves to RHS with -ve sign)
2x + 7 = 15 → 2x = 15-7 = 8 → x = 4
Simple Equations
Class 7
Check Solution
Substitute x back in original equation → LHS must equal RHS
x=5 in 3x+4=19: 3(5)+4=15+4=19 ✓
Triangles and Its Properties
Class 7
Angle sum in triangle
∠A + ∠B + ∠C = 180°
Angles 50°, 70°: third = 180-120 = 60°
Triangles and Its Properties
Class 7
Exterior angle theorem
Exterior angle = sum of opposite interior angles
Interior angles 65° and 75°: exterior angle = 65+75 = 140°
Triangles and Its Properties
Class 7
Pythagoras theorem
c² = a² + b²
c is hypotenuse (opposite to right angle)
Comparing Quantities
Class 7
Percentage
x% of y = (x/100) × y
Very commonly used in daily life
Comparing Quantities
Class 7
Profit %
Profit% = (Profit / CP) × 100 = (SP-CP)/CP × 100
CP=₹200, SP=₹250: Profit=₹50, Profit%=50/200×100=25%
Comparing Quantities
Class 7
Loss %
Loss% = (Loss / CP) × 100
CP=₹500, SP=₹400: Loss=₹100, Loss%=20%
Comparing Quantities
Class 7
Simple Interest
SI = P × R × T / 100
Amount = P + SI
Comparing Quantities
Class 7
Find SP from Profit%
SP = CP × (100 + Profit%) / 100
CP=₹800, Profit%=25: SP=800×125/100=₹1000
Rational Numbers
Class 7
a/b where b ≠ 0
a/b where b ≠ 0
Rational Numbers
Class 7
a/b = ac/bc
a/b = ac/bc
Visualising Solid Shapes
Class 7
Euler's formula: F + V - E = 2
Euler's formula: F + V - E = 2
Data Handling
Class 8
P(E) = Favourable outcomes / Total outcomes
P(E) = Favourable outcomes / Total outcomes
Exponents and Powers
Class 8
a⁻ⁿ = 1/aⁿ
a⁻ⁿ = 1/aⁿ
Exponents and Powers
Class 8
aᵐ × aⁿ = aᵐ⁺ⁿ
aᵐ × aⁿ = aᵐ⁺ⁿ
Exponents and Powers
Class 8
aᵐ/aⁿ = aᵐ⁻ⁿ
aᵐ/aⁿ = aᵐ⁻ⁿ
Exponents and Powers
Class 8
(aᵐ)ⁿ = aᵐⁿ
(aᵐ)ⁿ = aᵐⁿ
Linear Equations in One Variable
Class 8
Consecutive integers formula
n, n+1, n+2 (consecutive). n, n+2, n+4 (consecutive odd/even)
Sum of 4 consecutive integers = 4n+6. If =54: n=12, so 12,13,14,15
Rational Numbers
Class 8
Standard Form of Rational Number
p/q where HCF(p,q)=1 and q>0
-6/4 in standard form: divide by HCF(6,4)=2 → -3/2
Rational Numbers
Class 8
Multiplicative Inverse
Reciprocal of p/q = q/p
Reciprocal of 3/7 = 7/3. Reciprocal of -5/8 = -8/5
Comparing Quantities
Class 8
Discount
SP = MP - Discount = MP × (100-Discount%)/100
MP=₹800, Disc=25%: SP=800×75/100=₹600
Comparing Quantities
Class 8
GST Calculation
Amount paid = SP + (GST% × SP)/100 = SP×(100+GST%)/100
SP=₹2000, GST=18%: Amount=2000×118/100=₹2360
Comparing Quantities
Class 8
Compound Interest
A = P(1 + R/100)ⁿ | CI = A - P
n = number of years (or periods)
Comparing Quantities
Class 8
SI vs CI Difference
CI - SI = P(R/100)² (for 2 years)
P=₹5000, R=10%: CI-SI=5000×0.01=₹50
Mensuration
Class 8
Area of Trapezium
A = ½ × (a + b) × h
a,b are parallel sides; h is perpendicular height
Mensuration
Class 8
Cuboid TSA
TSA = 2(lb + bh + lh)
l=5, b=3, h=4: TSA=2(15+12+20)=94 cm²
Mensuration
Class 8
Cuboid Volume
V = l × b × h
l=5, b=3, h=4: V=60 cm³
Mensuration
Class 8
Cylinder CSA
CSA = 2πrh
r=7, h=10: CSA=2×22/7×7×10=440 cm²
Mensuration
Class 8
Cylinder Volume
V = πr²h
1000 cm³ = 1 litre
Factorisation
Class 8
a²-b² = (a+b)(a-b)
a²-b² = (a+b)(a-b)
Factorisation
Class 8
a²+2ab+b² = (a+b)²
a²+2ab+b² = (a+b)²
Cubes and Cube Roots
Class 8
Cube of a number
n³ = n × n × n
5³=125, 10³=1000, (-3)³=-27
Cubes and Cube Roots
Class 8
Cube root
∛n = m means m³ = n
∛125=5 because 5³=125. ∛(-125)=-5
Algebraic Expressions and Identities
Class 8
(a+b)² Identity
(a+b)^2 = a^2 + 2ab + b^2
(x+5)² = x²+10x+25. (2+3)²=4+12+9=25=5² ✓
Algebraic Expressions and Identities
Class 8
(a-b)² Identity
(a-b)^2 = a^2 - 2ab + b^2
(x-4)² = x²-8x+16
Algebraic Expressions and Identities
Class 8
Difference of squares
(a+b)(a-b) = a^2 - b^2
(x+7)(x-7)=x²-49. 103×97=(100)²-3²=9991
Direct and Inverse Proportions
Class 8
Direct: x/y = k (constant)
Direct: x/y = k (constant)
Direct and Inverse Proportions
Class 8
Inverse: x × y = k
Inverse: x × y = k
Squares and Square Roots
Class 8
√(a × b) = √a × √b
√(a × b) = √a × √b
Squares and Square Roots
Class 8
(a+b)² = a²+2ab+b²
(a+b)² = a²+2ab+b²
Squares and Square Roots
Class 8
(a-b)² = a²-2ab+b²
(a-b)² = a²-2ab+b²
Understanding Quadrilaterals
Class 8
Sum of angles of quadrilateral = 360°
Sum of angles of quadrilateral = 360°
Understanding Quadrilaterals
Class 8
Opposite angles of parallelogram are equal
Opposite angles of parallelogram are equal
Visualising Solid Shapes
Class 8
Euler's formula: F + V - E = 2
Euler's formula: F + V - E = 2
Areas of Parallelograms and Triangles
Class 9
Area = base × height
Area = base × height
Areas of Parallelograms and Triangles
Class 9
Area of triangle = ½ × b × h
Area of triangle = ½ × b × h
Heron's Formula
Class 9
s = (a+b+c)/2
s = (a+b+c)/2
Heron's Formula
Class 9
Area = √[s(s-a)(s-b)(s-c)]
Area = √[s(s-a)(s-b)(s-c)]
Linear Equations in Two Variables
Class 9
ax + by + c = 0
ax + by + c = 0
Lines and Angles
Class 9
Angle sum = 180°
Angle sum = 180°
Lines and Angles
Class 9
Vertically opposite angles are equal
Vertically opposite angles are equal
Number Systems
Class 9
Rationalising Factor
Multiply by conjugate: (a+√b)(a-√b) = a²-b
Rationalise 1/(√2+1): multiply by (√2-1)/(√2-1) = (√2-1)/(2-1) = √2-1
Number Systems
Class 9
Laws of Exponents
aᵐ × aⁿ = aᵐ⁺ⁿ | aᵐ/aⁿ = aᵐ⁻ⁿ | (aᵐ)ⁿ = aᵐⁿ
2³ × 2⁴ = 2⁷ = 128 | 3⁵/3² = 3³ = 27
Number Systems
Class 9
nth Root
a^(1/n) = ⁿ√a | a^(m/n) = ⁿ√(aᵐ)
8^(1/3) = ∛8 = 2 | 27^(2/3) = (∛27)² = 3² = 9
Polynomials
Class 9
Key Identities
(a+b)² = a²+2ab+b² (a-b)² = a²-2ab+b² (a+b)(a-b) = a²-b²
(x+3)² = x²+6x+9 | (2x-5)(2x+5) = 4x²-25
Polynomials
Class 9
Cubic Identities
(a+b)³ = a³+3a²b+3ab²+b³ (a-b)³ = a³-3a²b+3ab²-b³ a³+b³ = (a+b)(a²-ab+b²) a³-b³ = (a-b)(a²+ab+b²)
(x+2)³ = x³+6x²+12x+8
Polynomials
Class 9
Special: a³+b³+c³
If a+b+c=0, then a³+b³+c³ = 3abc
If x+y+z=0, then x³+y³+z³ = 3xyz
Probability
Class 9
P(E) = n(favorable outcomes)/n(total outcomes)
P(E) = n(favorable outcomes)/n(total outcomes)
Statistics
Class 9
Mean = Σx/n
Mean = Σx/n
Statistics
Class 9
Mode = most frequent value
Mode = most frequent value
Surface Areas and Volumes
Class 9
Cylinder
CSA=2πrh | TSA=2πr(r+h) | V=πr²h
π ≈ 22/7 ≈ 3.14159
Surface Areas and Volumes
Class 9
Cone
l=√(r²+h²) | CSA=πrl | TSA=πr(r+l) | V=⅓πr²h
r=3, h=4: l=5, V=⅓×π×9×4≈37.7 cm³
Surface Areas and Volumes
Class 9
Sphere
SA=4πr² | V=4/3 πr³
r=6cm: SA=4π×36≈452.4 cm² | V=4/3×π×216≈904.8 cm³
Surface Areas and Volumes
Class 9
Hemisphere
CSA=2πr² | TSA=3πr² | V=2/3 πr³
r=7: TSA=3×22/7×49=462 cm²

Science

58 formulas
Acids, Bases and Salts
Class 10
pH < 7 = acid
pH < 7 = acid
Acids, Bases and Salts
Class 10
pH > 7 = base
pH > 7 = base
Acids, Bases and Salts
Class 10
pH = 7 = neutral
pH = 7 = neutral
Electricity
Class 10
Ohm's Law
V = IR (V=voltage, I=current, R=resistance)
V=12V, R=4Ω: I=V/R=12/4=3A
Electricity
Class 10
Series Resistance
R_total = R₁ + R₂ + R₃
3Ω + 5Ω + 2Ω = 10Ω
Electricity
Class 10
Parallel Resistance
1/R_eq = 1/R₁ + 1/R₂ + 1/R₃
6Ω and 3Ω in parallel: 1/R=1/6+1/3=1/2 → R=2Ω
Electricity
Class 10
Electrical Power
P = VI = I²R = V²/R
I=2A, R=5Ω: P=I²R=4×5=20W
Electricity
Class 10
Electrical Energy
E = P × t = VIt
1000W heater for 2 hours: E=1000×7200=7,200,000 J = 2 kWh
Electricity
Class 10
Heating Effect (Joule)
H = I²Rt
I=3A, R=10Ω, t=60s: H=9×10×60=5400 J
Light — Reflection and Refraction
Class 10
1/v + 1/u = 1/f
1/v + 1/u = 1/f
Light — Reflection and Refraction
Class 10
m = -v/u
m = -v/u
Light — Reflection and Refraction
Class 10
n = sin i/sin r
n = sin i/sin r
Light — Reflection and Refraction
Class 10
P = 1/f (in metres)
P = 1/f (in metres)
Components of Food
Class 6
Iodine Test for Starch
Food + Iodine solution → Blue-black colour = starch present
Rice: blue-black (starch present). Onion: no colour change (no starch)
Motion and Measurement of Distances
Class 6
Unit Conversions
1 km = 1000 m = 100,000 cm = 10,00,000 mm
Your height 160cm = 1.6m = 0.0016km
Motion and Measurement of Distances
Class 6
Time
1 hour = 60 minutes = 3600 seconds
2.5 hours = 150 minutes = 9000 seconds
Getting to Know Plants
Class 6
Photosynthesis Equation
CO₂ + H₂O + Sunlight → Glucose + O₂
Chlorophyll in leaves captures sunlight energy
Light, Shadows and Reflections
Class 6
Law of Reflection
Angle of incidence = Angle of reflection
Light hits mirror at 40° → reflects at 40° (both measured from normal)
Heat
Class 7
Temperature Conversion
F = (9/5)C + 32 | C = (F-32) × 5/9
Normal body temperature
Heat
Class 7
Kelvin to Celsius
K = C + 273
0°C = 273K (freezing of water). -273°C = 0K (absolute zero)
Acids, Bases and Salts
Class 7
Neutralisation
Acid + Base → Salt + Water
HCl + NaOH → NaCl + H₂O (table salt + water)
Acids, Bases and Salts
Class 7
pH Scale
pH 0-6: acid (lower = stronger). pH 7: neutral. pH 8-14: base (higher = stronger)
Battery acid: pH 1. Lemon: pH 2. Blood: pH 7.4. Baking soda: pH 9. Drain cleaner: pH 14
Respiration in Organisms
Class 7
Glucose + Oxygen → CO₂ + Water + Energy
Glucose + Oxygen → CO₂ + Water + Energy
Respiration in Organisms
Class 7
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy
Nutrition in Plants
Class 7
Photosynthesis Equation
6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂
Occurs in chloroplasts of leaf cells
Physical and Chemical Changes
Class 7
Rusting (simplified)
Iron + Oxygen + Water → Iron Oxide (rust)
4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃ → Fe₂O₃ (rust)
Motion and Time
Class 7
Speed
Speed = Distance / Time
SI unit is m/s
Motion and Time
Class 7
Unit Conversion
1 km/h = 5/18 m/s | 1 m/s = 18/5 km/h = 3.6 km/h
72 km/h = 72×5/18 = 20 m/s
Motion and Time
Class 7
Pendulum Time Period
T = 2π√(L/g)
T depends only on length L, not mass
Motion and Time
Class 7
Distance from Graph
Distance = Speed × Time = Area under speed-time graph
Speed=40m/s for 5s: Distance=40×5=200m
Microorganisms: Friend and Foe
Class 8
Pasteurization Temperature
Milk heated to 70°C for 15 seconds OR 63°C for 30 minutes
Developed by Louis Pasteur in 1864
Metals and Non-metals
Class 8
Reactivity Series (decreasing)
K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au
More reactive metal displaces less reactive from solution
Light
Class 8
Law of Reflection
Angle of incidence (i) = Angle of reflection (r)
Light hits mirror at 35°: reflects at 35°
Light
Class 8
Speed and Refractive Index
n = c/v (refractive index = speed in vacuum / speed in medium)
Glass n≈1.5: light slows to c/1.5 = 2×10⁸ m/s
Combustion and Flame
Class 8
Calorific value = Energy released per kg of fuel
Calorific value = Energy released per kg of fuel
Force and Pressure
Class 8
Pressure = Force / Area
Pressure = Force / Area
Force and Pressure
Class 8
P = F/A
P = F/A
Sound
Class 8
Speed of Sound
Speed = Distance / Time (like all speed)
Speed varies with temperature and medium
Sound
Class 8
Echo Minimum Distance
Minimum distance = (Speed of sound × 0.1s) / 2 = 17.15 m
Human ear cannot distinguish sounds less than 0.1s apart
Sound
Class 8
Frequency and Pitch
Higher frequency → Higher pitch (shriller sound)
Whistle: ~3000 Hz (high pitch). Bass drum: ~50-100 Hz (low pitch)
Atoms and Molecules
Class 9
Law of conservation of mass
Law of conservation of mass
Atoms and Molecules
Class 9
Law of constant proportions
Law of constant proportions
Gravitation
Class 9
F = Gm₁m₂/r²
F = Gm₁m₂/r²
Gravitation
Class 9
g = GM/R²
g = GM/R²
Gravitation
Class 9
W = mg
W = mg
Motion
Class 9
Speed
v = d/t
Car travels 120 km in 2h: v = 120/2 = 60 km/h
Motion
Class 9
1st Equation of Motion
v = u + at
u=initial velocity, v=final velocity, a=acceleration, t=time
Motion
Class 9
2nd Equation of Motion
s = ut + ½at²
u=0, a=10, t=5: s=0+½×10×25=125m
Motion
Class 9
3rd Equation of Motion
v² = u² + 2as
u=0, a=10, s=20: v²=400, v=20m/s
Motion
Class 9
Average Velocity (uniform acc)
v_avg = (u+v)/2
u=10, v=30: avg=20 m/s
Force and Laws of Motion
Class 9
Newton's Second Law
F = ma = Δp/Δt
F in Newtons, m in kg, a in m/s²
Force and Laws of Motion
Class 9
Momentum
p = mv
Truck: 5000kg×20m/s = 100,000 kg⋅m/s | Ball: 0.1kg×30m/s = 3 kg⋅m/s
Force and Laws of Motion
Class 9
Impulse
Impulse = F × t = Δp = m(v-u)
Bat hits ball: F=500N for 0.02s → Impulse=10 N⋅s
Force and Laws of Motion
Class 9
Conservation of Momentum
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
2kg at 5m/s hits 3kg at rest: 10=2v₁+3v₂. If stick: v=(10)/5=2 m/s
Work and Energy
Class 9
W = F × s
W = F × s
Work and Energy
Class 9
KE = ½mv²
KE = ½mv²
Work and Energy
Class 9
PE = mgh
PE = mgh
Work and Energy
Class 9
P = W/t
P = W/t

Physics

61 formulas
Gravitation
Class 11
Universal Gravitation
F = Gm₁m₂/r²
G = 6.674×10⁻¹¹ N⋅m²/kg²
Gravitation
Class 11
g at surface
g = GM/R²
M=6×10²⁴kg, R=6.4×10⁶m: g=6.67×10⁻¹¹×6×10²⁴/(6.4×10⁶)² ≈ 9.8 m/s²
Gravitation
Class 11
g at height h
g_h = g(R/(R+h))² ≈ g(1-2h/R) for h<<R
At h=R: g_h = g/4. At h=2R: g_h = g/9
Gravitation
Class 11
Orbital Velocity
v_o = √(GM/r) = √(gR²/r)
Near Earth surface (r≈R): v_o = √(9.8×6.4×10⁶) ≈ 7920 m/s ≈ 7.9 km/s
Gravitation
Class 11
Escape Velocity
v_e = √(2GM/R) = √(2gR) = √2 × v_o
v_e = √(2×9.8×6.4×10⁶) ≈ 11,200 m/s ≈ 11.2 km/s
Gravitation
Class 11
Kepler's 3rd Law
T² ∝ r³ → T₁²/T₂² = r₁³/r₂³
Earth: T=1yr, r=1AU. Mars: r=1.52AU → T²=1.52³=3.51 → T=1.88 years
Laws of Motion
Class 11
F = ma
F = ma
Laws of Motion
Class 11
p = mv
p = mv
Laws of Motion
Class 11
Impulse = Δp
Impulse = Δp
Motion in a Plane
Class 11
Range = u²sin2θ/g
Range = u²sin2θ/g
Motion in a Plane
Class 11
Maximum height = u²sin²θ/2g
Maximum height = u²sin²θ/2g
Motion in a Plane
Class 11
Time of flight = 2usinθ/g
Time of flight = 2usinθ/g
Motion in a Straight Line
Class 11
1st Equation of Motion
v = u + at
u=initial velocity, v=final velocity
Motion in a Straight Line
Class 11
2nd Equation of Motion
s = ut + ½at²
u=0, a=10, t=3: s=0+½×10×9=45 m
Motion in a Straight Line
Class 11
3rd Equation of Motion
v² = u² + 2as
u=0, a=10, s=20: v²=400, v=20 m/s
Motion in a Straight Line
Class 11
Distance in nth second
sₙ = u + a(2n-1)/2
Distance in the nth second (not total)
Motion in a Straight Line
Class 11
Average Velocity
v_avg = (u+v)/2 [only for uniform acceleration]
u=10, v=30: avg=20 m/s
Oscillations
Class 11
T = 2π√(l/g)
T = 2π√(l/g)
Oscillations
Class 11
T = 2π√(m/k)
T = 2π√(m/k)
System of Particles and Rotational Motion
Class 11
τ = r×F
τ = r×F
System of Particles and Rotational Motion
Class 11
L = Iω
L = Iω
System of Particles and Rotational Motion
Class 11
τ = Iα
τ = Iα
Waves
Class 11
v = fλ
v = fλ
Waves
Class 11
v = √(T/μ)
v = √(T/μ)
Work, Energy and Power
Class 11
W = F·d·cosθ
W = F·d·cosθ
Work, Energy and Power
Class 11
KE = ½mv²
KE = ½mv²
Work, Energy and Power
Class 11
P = W/t
P = W/t
Alternating Current
Class 12
Vrms = V₀/√2
Vrms = V₀/√2
Alternating Current
Class 12
Z = √(R²+X²)
Z = √(R²+X²)
Alternating Current
Class 12
P = VrmsIrms cosφ
P = VrmsIrms cosφ
Atoms
Class 12
rn = 0.529n² Å
rn = 0.529n² Å
Atoms
Class 12
En = -13.6/n² eV
En = -13.6/n² eV
Current Electricity
Class 12
I = nAvde
I = nAvde
Current Electricity
Class 12
R = ρl/A
R = ρl/A
Current Electricity
Class 12
Kirchhoff: ΣI=0, ΣV=0
Kirchhoff: ΣI=0, ΣV=0
Dual Nature of Radiation and Matter
Class 12
E = hν
E = hν
Dual Nature of Radiation and Matter
Class 12
KEmax = hν - W₀
KEmax = hν - W₀
Dual Nature of Radiation and Matter
Class 12
λ = h/mv
λ = h/mv
Electric Charges and Fields
Class 12
Coulomb's Law
F = kq₁q₂/r² = q₁q₂/(4πε₀r²)
k = 9×10⁹ N⋅m²/C²
Electric Charges and Fields
Class 12
Electric Field
E = F/q₀ = kq/r² (point charge)
q₀ is positive test charge
Electric Charges and Fields
Class 12
Gauss's Law
φ = ∮E⃗⋅dA⃗ = Q_enc/ε₀
Charge Q inside sphere of any radius: φ = Q/ε₀ (same for any closed surface!)
Electric Charges and Fields
Class 12
Field due to Line Charge
E = λ/(2πε₀r)
λ=1μC/m, r=0.1m: E=10⁻⁶/(2π×8.85×10⁻¹²×0.1)=1.8×10⁵ N/C
Electromagnetic Induction
Class 12
EMF = -dΦ/dt
EMF = -dΦ/dt
Electromagnetic Induction
Class 12
EMF = Blv
EMF = Blv
Electromagnetic Induction
Class 12
L = NΦ/I
L = NΦ/I
Electrostatic Potential and Capacitance
Class 12
V = kq/r
V = kq/r
Electrostatic Potential and Capacitance
Class 12
C = Q/V
C = Q/V
Electrostatic Potential and Capacitance
Class 12
U = ½CV²
U = ½CV²
Electrostatic Potential and Capacitance
Class 12
Series: 1/C = 1/C₁+1/C₂
Series: 1/C = 1/C₁+1/C₂
Moving Charges and Magnetism
Class 12
F = qv×B
F = qv×B
Moving Charges and Magnetism
Class 12
B = μ₀I/2πr (wire)
B = μ₀I/2πr (wire)
Moving Charges and Magnetism
Class 12
B = μ₀nI (solenoid)
B = μ₀nI (solenoid)
Nuclei
Class 12
E = mc²
E = mc²
Nuclei
Class 12
ΔE = Δm × c²
ΔE = Δm × c²
Ray Optics
Class 12
Mirror: 1/v+1/u=1/f
Mirror: 1/v+1/u=1/f
Ray Optics
Class 12
Lens: 1/v-1/u=1/f
Lens: 1/v-1/u=1/f
Ray Optics
Class 12
n = sin i/sin r
n = sin i/sin r
Wave Optics
Class 12
YDSE Fringe Width
β = λD/d
β = distance between consecutive bright (or dark) fringes
Wave Optics
Class 12
Path Difference
Bright: Δ=nλ (n=0,±1,±2...) | Dark: Δ=(2n+1)λ/2
For 3rd bright fringe: Δ=3λ. For 2nd dark: Δ=3λ/2
Wave Optics
Class 12
Intensity Pattern
I = 4I₀cos²(δ/2) where δ = phase difference = 2πΔ/λ
At bright fringe: δ=0,2π: I=4I₀ (maximum)
Wave Optics
Class 12
Brewster's Law
tan(θ_B) = n (refractive index)
Glass n=1.5: θ_B=arctan(1.5)=56.3°

Chemistry

10 formulas

Biology

3 formulas

Accountancy

18 formulas
Bank Reconciliation Statement
Class 11
Balance as per cash book ± Adjustments = Balance as per passbook
Balance as per cash book ± Adjustments = Balance as per passbook
Depreciation, Provisions and Reserves
Class 11
SLM = (Cost - Residual Value) / Useful life
SLM = (Cost - Residual Value) / Useful life
Depreciation, Provisions and Reserves
Class 11
WDV = Book value × Rate%
WDV = Book value × Rate%
Financial Statements — I
Class 11
Gross Profit = Net Sales - Cost of goods sold
Gross Profit = Net Sales - Cost of goods sold
Financial Statements — I
Class 11
Net Profit = Gross Profit - Indirect Expenses
Net Profit = Gross Profit - Indirect Expenses
Recording of Transactions — I
Class 11
Assets = Liabilities + Capital
Assets = Liabilities + Capital
Recording of Transactions — I
Class 11
Debit = Credit (in balanced accounts)
Debit = Credit (in balanced accounts)
Accounting for Partnership
Class 12
P&L Appropriation = Net Profit - Interest on Capital - Salary + Interest on Drawings
P&L Appropriation = Net Profit - Interest on Capital - Salary + Interest on Drawings
Accounting for Share Capital
Class 12
Securities Premium = Issue price - Face value
Securities Premium = Issue price - Face value
Accounting for Share Capital
Class 12
Capital Reserve = Proceeds from re-issue of forfeited shares
Capital Reserve = Proceeds from re-issue of forfeited shares
Accounting Ratios
Class 12
Current ratio = CA/CL
Current ratio = CA/CL
Accounting Ratios
Class 12
Quick ratio = (CA-Inventory)/CL
Quick ratio = (CA-Inventory)/CL
Accounting Ratios
Class 12
Gross profit ratio = GP/Net Sales × 100
Gross profit ratio = GP/Net Sales × 100
Accounting Ratios
Class 12
Net profit ratio = NP/Net Sales × 100
Net profit ratio = NP/Net Sales × 100
Accounting Ratios
Class 12
Return on equity = NP/Shareholders' equity × 100
Return on equity = NP/Shareholders' equity × 100
Dissolution of Partnership
Class 12
Realisation account closes with profit/loss on realisation
Realisation account closes with profit/loss on realisation
Reconstitution of Partnership
Class 12
Goodwill = Super profit × Years of purchase
Goodwill = Super profit × Years of purchase
Reconstitution of Partnership
Class 12
Gaining ratio = New ratio - Old ratio
Gaining ratio = New ratio - Old ratio

Business Studies

3 formulas

Economics

22 formulas
Correlation
Class 11
r = Σdx·dy / √(Σdx² × Σdy²)
r = Σdx·dy / √(Σdx² × Σdy²)
Measures of Central Tendency
Class 11
Mean = ΣX/N
Mean = ΣX/N
Measures of Central Tendency
Class 11
Median = L + (N/2 - CF)/f × h
Median = L + (N/2 - CF)/f × h
Measures of Dispersion
Class 11
SD = √(Σfd²/N)
SD = √(Σfd²/N)
Measures of Dispersion
Class 11
CV = (SD/Mean) × 100
CV = (SD/Mean) × 100
Determination of Income and Employment
Class 12
Income = Consumption + Saving
Income = Consumption + Saving
Determination of Income and Employment
Class 12
MPC = ΔC/ΔY
MPC = ΔC/ΔY
Determination of Income and Employment
Class 12
MPS = ΔS/ΔY
MPS = ΔS/ΔY
Determination of Income and Employment
Class 12
MPC + MPS = 1
MPC + MPS = 1
Determination of Income and Employment
Class 12
Multiplier = 1/(1-MPC)
Multiplier = 1/(1-MPC)
Government Budget and the Economy
Class 12
Fiscal deficit = Total expenditure - Revenue receipts - Non-debt capital receipts
Fiscal deficit = Total expenditure - Revenue receipts - Non-debt capital receipts
Government Budget and the Economy
Class 12
Primary deficit = Fiscal deficit - Interest payments
Primary deficit = Fiscal deficit - Interest payments
National Income Accounting
Class 12
GDP = C + I + G + (X-M)
GDP = C + I + G + (X-M)
National Income Accounting
Class 12
NNP = GNP - Depreciation
NNP = GNP - Depreciation
National Income Accounting
Class 12
National income = NNP - Indirect taxes + Subsidies
National income = NNP - Indirect taxes + Subsidies
Production and Costs
Class 12
TC = TFC + TVC
TC = TFC + TVC
Production and Costs
Class 12
MC = ΔTC/ΔQ
MC = ΔTC/ΔQ
Production and Costs
Class 12
ATC = TC/Q
ATC = TC/Q
The Theory of the Firm Under Perfect Competition
Class 12
Profit = TR - TC
Profit = TR - TC
The Theory of the Firm Under Perfect Competition
Class 12
MR = MC (equilibrium)
MR = MC (equilibrium)
Theory of Consumer Behaviour
Class 12
MUx/Px = MUy/Py (Cardinal)
MUx/Px = MUy/Py (Cardinal)
Theory of Consumer Behaviour
Class 12
MRSxy = Px/Py (Ordinal)
MRSxy = Px/Py (Ordinal)