Class 8 Maths Formulas

Class 8 maths formulas are a stepping stone towards the preparation of board exams ahead. Hence, it is essential to understand and learn them well. The anxiety that crops up in students is understandable as math formulas are complex to learn. To make things simple for students this article covers all the 8th grade math formulas in a concise manner to help students overcome the learning hurdle and keep their calm during the exams.

The important class 8 math formulas listed in this article will not only help the students understand their relevance easily, but will also get them acquainted with some practical tips to learn them which can easily be implemented in routine.

List of Important Class 8 Math Formulas  

Here is a summarized list of Class 8 math formulas that can be used.

• Additive inverse of rational number: a/b = -b/a
• Multiplicative Inverse of a/b = c/d , if a/b × c/d = 1
• Distributivity a(b - c) = ab - ac
• Probability of the occurrence of an event = Number of outcomes that comprise an event/ Total number of outcomes
• Compound Interest formula = Amount - Principal, Amount in case the interest is to be calculated annually = Principal ( 1 + Rate/100)ⁿ, where ‘n’ is the time period.
• (a - b)² = a² - 2ab + b²
• (a + b) (a - b) = a² - b²  
• Euler’s Formula: For any polyhedron, Number of faces + Number of vertices - Number of edges = 2
• Volume of a Cone = (1 / 3 )πr²h
• Volume of a Sphere = (4/3) π r³

Rational Numbers Class 8 Math Formulas

Integers, real numbers, natural numbers, whole numbers, fractional numbers, prime numbers, composite numbers are the different types of numbers in arithmetic. Rational Numbers Class 8 math formulas cover the different entities of rational numbers that will help the students understand the concept of rational numbers, their uniqueness from the rest of the numbers and their usage in higher arithmetic.

Any number that can be written in the form of a ⁄ b where b ≠ 0 are rational numbers. The properties of rational numbers are as follows:

• Additive Identity states (a ⁄ b + 0) = (a ⁄ b)
• Multiplicative Identity states (a ⁄ b) × 1 = (a/b)
• Multiplicative Inverse states (a ⁄ b) × (b/a) = 1

Geometry Solid Shapes Class 8 Math Formulas

Solid geometry plays an important part in everyday life since it aids in understanding the various shapes that surround us and their qualities. Students will benefit from a strong understanding of visualization of solid objects in learning more complicated geometry concepts, and in solving real-world problems. Hence, it becomes essential to learn about the various formulas associated with different solids that will help in everyday calculations.

• Curved Surface Area of a Cone = 1 /2 × l × 2πr = πrl, where ‘r’ is its base radius and ‘l’ its slant height. ‘l’ = √(r² + h²)
• Volume of a Cuboid = Base Area × Height = Length × Breadth × Height
• Volume of a Cone = (1 / 3 )πr²h
• Volume of a Sphere = (4/3) π r³
• Volume of a Hemisphere = (2/3) πr³

Data Handling Formulas for Class 8 Maths

Any problem that we need to investigate necessitates the gathering of data, which must then be displayed in such a way that it gives a clear visual of the problem's details while also analyzing the solutions that are possible. For this the students need to familiarize themselves with various concepts related to data handling. One such concept that falls within data handling is probability which helps in the prediction of events. Probability is the mathematical term for possibility of occurrence.

Probability = Number of outcomes making up an event / Total number of outcomes, if the outcomes are equally likely.

Exponents Formulas for Class 8 Maths

An exponent represents the value which refers to the number of times a number is multiplied by itself. For example, 5 × 5 × 5 can be written as 53. Even very small numbers can be expressed in the form of negative exponents. Here is a list of some of the laws related to exponents:

• Law of Product: a^m × aⁿ = a^{m + n}
• Law of Quotient: a^m/aⁿ = a^{m - n}
• Law of Zero Exponent: a⁰ = 1
• Law of Negative Exponent: a^-m = 1/a^m
• Law of Power of a Power: (a^m)ⁿ = a^mn
• Law of Power of a Product: (ab)^m = a^mb^m
• Law of Power of a Quotient: (a/b)^m = a^m/b^m

Comparing Quantities Formulas for Class 8 Maths

The following formulas will help students understand the basics of simple arithmetic involving money.

• Discount = Marked Price - Sale Price
• Simple Interest = ( Principal × Rate × Time )/100
• Compound Interest Formula = Amount - Principal

If the interest is to be calculated annually, then Amount = Principal ( 1 + Rate/100)ⁿ, ‘n’ is the time period.

Algebra for Class 8 Maths

Algebraic expressions and Identities are one of the most important and interesting concepts to understand the nature of mathematics. Factorization of an algebraic expression results in a product of factors. These factors can be numbers, algebraic variables or expressions. The following three identities hold true for any value of the variables.

• (a + b)² = a² + 2ab + b²
• (a + b) (a - b) = a² - b²
• (a - b)² = a² - 2ab + b²

Applications of Class 8 Maths Formulas

Math is present in practically every activity that we engage in our daily lives. The formulation of these arithmetic formulas was based on an analytical examination of how to address challenges encountered in everyday life.

• The class 8 maths formulas related to data handling and probability help in taking out meaningful inferences and the prediction of events.
• The class 8 maths formulas related to exponents and powers help in making the complex calculations encountered in mathematics very easy. The laws of exponents are a quick way to understand the mathematics of large numbers.
• The algebraic entities are an interesting way to solve the value of the unknown for any given problem.

Tips to Memorize Class 8 Maths formulas

To excel in maths it is essential to get a good grasp of the class 8 math formulas. However, at the same time the students need not worry and get anxious as below are some of the tips that they can follow to memorize the formulas effectively.

• Positive Outlook: Firstly, it is important to relax. Having a positive outlook eases out any task on its own. Rather than getting anxious at the sight of formulas, the students are advised to chalk out a plan for themselves in which they can spread out the chapters or topics over a span of days rather than trying to learn everything in one day. 
• Keep a List of Formulas: Secondly, it will be very helpful if the students keep only one list of formulas for their reference. It could be like a formula wallpaper on their device or laptop screens. Keeping multiple checklists will only lead to more anxiety and confusion.
• Practice consistently: Thirdly, to excel in maths, consistent practice goes a long way. The students are advised to solve as many problems as they can as this exposes them to the usage of different formulas. This in itself is a good way to remember formulas without the hassle of mugging them up. Class 8 Maths formulas Examples

Example 1: Solve the given expression using the law of exponents:  40⁵ × 40²

Solution: 

We will solve the expression using the Law of Product: a^m × aⁿ = a^m+n

 40⁵ × 40²  = 40⁵⁺²

= 40⁷          

Example 2 : The height of a cylinder needs to be calculated whose radius is 6 cm and the total surface area is 900 cm²

Solution: Let us assume the height of the cylinder = h, radius = 6 cm 

Total surface area of cylinder = 2πr (h + r) 

Substituting the values in the given equation:

900 = 2 × 22/7 × 6 (h + 6)

h = 17.87

Hence, the height of the cylinder is 17.87 cm.

Students can download the printable Maths Formulas Class 8 sheet from below: