8th Class Maths Formulas List (2024-25) | TIRLA ACADEMY

Hello Readers,

Formulas play an important role in solving various maths problems. Because of its importance, Here we provide a chapter-wise list of formulas for class 8th.


Rational Numbers

⇒ The rational number 0 is the additive identity for rational numbers.

⇒ The rational number 1 is the multiplicative identity for rational numbers.


Understanding Quadrilaterals

⇒ The sum of all interior angles of a Polygon = 180(n-2)

⇒ The sum of all the exterior angles of Polygon = 360°

⇒ The sum of all the interior angles of the Triangle = 180°

⇒ The sum of all the interior angles of the Quadrilateral = 360°

⇒ Exterior angle of Regular Polygon = 360°/No. of Sides

⇒ No. of sides of Regular Polygon = 360°/Exterior Angle

⇒ Exterior Angle = 180° - Interior Angle

⇒ The minimum interior angle possible for a regular polygon = 60°.

⇒ The maximum exterior angle possible for a regular polygon = 120°.

⇒ Perimeter of parallelogram = Sum of all sides.

⇒ The sum of any two adjacent angles of Parallelogram = 180°

⇒ The sum of all the interior angles of the Parallelogram = 360°


Data Handling

⇒ Total angle at the center of a circle = 360°.

⇒ Probability = (No. of favorable Outcomes of an event)/(Total no. of Outcomes)


Squares and Square roots

⇒ All square numbers end with 0, 1, 4, 5, 6, or 9 at unit place.

⇒ To find the numbers that lie between the squares of two consecutive numbers = 2n

⇒ To Find the square of the number-

(a+b)²=a²+2ab+b²

(a-b)²=a²-2ab+b²

⇒ Pythagorean Triplet:- 2m, m²-1, m²+1

⇒ Area of square = Side×Side

⇒ Pythagoras Theorem:- H² = P² + B²


Cubes and Cube roots

⇒ Volume of Cuboid = Length×Breadth×Height

⇒ The volume of Cube = (Length of side)³


Comparing Quantities

⇒ 1km = 100m

⇒ 1Rs. = 100paise

⇒ Discount = Marked Price - Sale Price

⇒ Discount % = (Discount price×100)/Marked Price

⇒ Simple Interest = (P×R×T)/100

⇒ Amount = Principal + Interest

⇒ Amount = Principal×[1+(Rate/100)]ⁿ

⇒ Compound Interest = Amount - Principal


Algebraic Expressions and Identities

⇒ Area of Rectangle = Length × Breadth

⇒ The volume of the Rectangular Box = Length×Breadth×Height

⇒ (a+b)(a-b)=a²-b²


Mensuration

⇒ Area of Triangle = 1/2×b×h

⇒ Area of Trapezium = h/2×(a+b)

⇒ Area of Quadrilateral = D/2(H+H)

⇒ Area of Rhombus = 1/2×D₁×D

⇒ Area of Rectangle = Length × Breadth

⇒ Area of Square = Side×Side

⇒ Total Surface Area of Cube = 6×(Length of side)²

⇒ Lateral Surface Area of Cube = 4×(Length of side)²

⇒ Total Surface Area of Cuboid = 2(lb+bh+hl)

⇒ Lateral Surface Area of Cuboid = 2(bh+hl)

⇒ Total Surface Area of Cylinder = 2𝜋r(r+h)

⇒ Curved Surface Area of Cylinder = 2𝜋rh

⇒ Volume of Cube = (Length of side)³

⇒ Volume of Cuboid = Length×Breadth×Height

⇒ Height of Cuboid = Volume of Cuboid/Base Area

⇒ Volume of Cylinder = 𝜋r²h

⇒ 1 Litre = 1000cm³

⇒ 1 m³ = 1000 Litre

⇒ 1 m³ = 1000000cm³

⇒ 1ml = 1cm³

⇒ 1m = 100cm


Exponents and Powers

⇒ a- = 1/a

⇒ a×a=a

⇒ a÷a=a

⇒ (a)=a

⇒ a×b=(ab)

⇒ a÷b=(a÷b)

⇒ a° = 1


Direct and Inverse Proportions

⇒ Direct Proportion x/y = x/y

⇒ Inverse Proportion xy = xy


Factorisation

⇒ (a+b)²=a²+2ab+b²

⇒ (a-b)²=a²-2ab+b²

⇒ (a+b)(a-b)=a²-b²

⇒ (x+a)(x+b)=x²+(a+b)x+ab