CBSE Class 8 Maths Formulas with Examples

CBSE Class 8 Maths Formulas

Maths is a subject that becomes easy when students clearly understand the concepts and remember the important formulas. For Class 8 students, formulas are the key to solving problems quickly and scoring good marks in exams. Instead of memorising randomly, learning formulas chapter-wise helps in better understanding and long-term retention.

This article provides a complete list of Class 8 Maths formulas, explained in simple words, along with examples and frequently asked questions. It is helpful for exam preparation, quick revision, and daily practice.

Read More: A^2-B^2 Formula

Rational Numbers Class 8 Maths Formulas

Rational numbers are numbers that can be expressed in the form p/q, where p and q are integers and q ≠ 0. They include positive, negative, and zero values.

Important Formulas:

Standard form of rational number: p/q where q > 0

Addition: a/b + c/d = (ad + bc) / bd

Subtraction: a/b − c/d = (ad − bc) / bd

Multiplication: (a/b) × (c/d) = ac / bd

Division: (a/b) ÷ (c/d) = (a/b) × (d/c)

Example:

1/3 + 2/5 = (5 + 6) / 15 = 11/15

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Geometry – Solid Shapes Class 8 Maths Formulas

Solid shapes are three-dimensional objects that have length, breadth, and height. Common solid shapes include cube, cuboid, cylinder, cone, and sphere.

Important Formulas:

Cuboid

Volume = l × b × h

Total Surface Area = 2(lb + bh + hl)

Cube

Volume = a³

Total Surface Area = 6a²

Cylinder

Curved Surface Area = 2πrh

Total Surface Area = 2πr(r + h)

Volume = πr²h

Example:

Volume of a cuboid with length 5 cm, breadth 4 cm, height 3 cm

= 5 × 4 × 3 = 60 cm³

Read More: Section Formula

Data Handling Class 8 Maths Formulas

Data handling helps students organise, represent, and analyse information using tables, graphs, and charts.

Important Concepts:

Mean = Sum of observations / Number of observations

Range = Highest value − Lowest value

Pie chart angle = (Value / Total value) × 360°

Example:

Mean of 3, 5, 7, 9 = (3+5+7+9)/4 = 6

Probability Class 8 Maths Formulas

Probability tells us how likely an event is to occur. The value of probability always lies between 0 and 1.

Formula:

Probability of an event = Number of favourable outcomes / Total possible outcomes

Example:

Probability of getting an even number on a dice

= 3/6 = 1/2

Read More: What is Pi

Exponents and Powers Class 8 Maths Formulas

Exponents are used to represent repeated multiplication of numbers. This chapter also introduces the standard form of large numbers.

Laws of Exponents:

aᵐ × aⁿ = aᵐ⁺ⁿ

aᵐ ÷ aⁿ = aᵐ⁻ⁿ 

(aᵐ)ⁿ = aᵐⁿ

a⁰ = 1 (a ≠ 0)

a⁻ᵐ = 1 / aᵐ

Example:

10⁻² = 1/100

Comparing Quantities Class 8 Maths Formulas

This chapter is very useful in daily life. It includes percentages, profit and loss, discount, simple interest, and compound interest.

Important Formulas:

Percentage = (Value / Total value) × 100

Profit = Selling Price − Cost Price

Loss = Cost Price − Selling Price

Discount = Marked Price − Selling Price

Simple Interest (SI) = (P × R × T) / 100

Amount = Principal + Interest

Example:

If CP = ₹500 and SP = ₹650

Profit = 650 − 500 = ₹150

Also Read: Loss Percentage Formula

Algebra Class 8 Maths Formulas

Algebra involves the use of letters and symbols to represent numbers and solve equations.

Important Identities:

(a + b)² = a² + 2ab + b²

(a − b)² = a² − 2ab + b²

a² − b² = (a + b)(a − b)

Example:

(a + 5)² = a² + 10a + 25

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