Class 9 Maths Formulas
Mathematics is often feared by students as it comes with the complexity of learning the formulas. A glimpse of formulas can raise the anxiety of students, and this is the reason many of them are reluctant to study the subject. To help students calm down and have an easy approach to learning the class 9 math formulas, this article provides a summary of all the important formulas and some helpful tips to remember them.
List of Important Class 9 Math Formulas
Here is a summarized list of the important Class 9 Math formulas.
 (a + b) (a  b) = a^{2}  b^{2}
 (a + b)^{2} = a^{2} + 2ab + b^{2}
 (a  b)^{3} = a^{3}  b^{3}  3ab(a  b)
 Heron’s Formula to find the area of a triangle = √s(s  a)(s  b)(s  c), where ‘s’ is the semi perimeter of the triangle and is calculated with the formula, s = (a + b + c)/2
 Curved Surface Area of a Cone = 1 /2 × l × 2πr = πrl, where ‘r’ is its base radius and ‘l’ its slant height. ‘l’ = Square root of (r^{2} + h^{2})
 Volume of a Cuboid = Base Area × Height = Length × Breadth × Height
 Volume of a Cone = (1 / 3 )πr^{2}h
 Volume of a Sphere = (4/3) π r^{3}
 Volume of a Hemisphere = (2/3) πr^{3}
 Mean = Sum of the observations / Total number of observations
Number System Class 9 Math Formulas
Number system class 9 math formulas cover important facts about rational and irrational numbers which help to strengthen the math foundation. Suppose, a number ‘a’ is rational, and ‘b’ is irrational, then ‘a + b’, and ‘a  b’ are irrational numbers, ‘ab’ and ‘a/b’ are irrational numbers, and ‘b’ is not equal to zero.
For ‘a’ and ‘b’ positive real numbers the following entities will be true:
 √ab = √a √b
 √(a/b) = √a / √b
 (√a + √b) (√a  √b) = a  b
 (√a + √b)^{2} = a + 2√ab + b
 (a + √b) (a  √b) = a^{2}  b
 (a + b) (a  b) = a^{2}  b^{2}
Algebra Formulas for Class 9 Maths
The fundamental properties and theorems of polynomials form the building blocks for higher algebra polynomials. The process of factorization of polynomials helps in finding the roots of an equation, and it is an important concept that can improve the understanding of algebra in students.
 (a + b)^{2} = a^{2} + 2ab + b^{2}
 (a  b)^{3} = a^{3}  b^{3}  3ab(a  b)
Area and Volume Class 9 Math Formulas
We come across shapes of all sorts in our daily life, and hence, the need to find their measurements arise, further leading to calculations of area and volume. These calculations are required in daily life whether one needs to figure out how much liquid is needed to fill a container or one needs to calculate the surface area of any object. The class 9 maths formulas regarding the same can be found as below:
 Surface Area of a Cuboid = 2(lb + bh + hl), where ‘l’, ‘b’ and ‘h’ are the length, breadth, and height respectively.
 Curved Surface Area of a Cone = 1 /2 × l × 2πr = πrl, where ‘r’ is its base radius and ‘l’ its slant height
Then, ‘l’ = Square root of (r^{2} + h^{2})
 Surface Area of a Sphere = 4 π r^{2}
 Volume of a Cuboid = Base Area × Height = Length × Breadth × Height
 Volume of a Cube = a^{3} where ‘a’ is the edge of the cube.
 Volume of a Cylinder = πr^{2}h , where, ‘r’ and ‘h’ are radius and height respectively.
 Volume of a Cone = (1 / 3)πr^{2}h
 Volume of a Sphere = (4/3) πr^{3}
 Volume of a Hemisphere = (2/3) πr^{3}
Statistics and Probability Formulas for Class 9 Maths
Statistics plays a crucial role in practically every aspect of life. The concept of probability is all about the prediction of events, and the formulas regarding the same have their usage almost everywhere including the prediction of weather and several fields of science. To draw the essential conclusions from data, one must first learn how to analyze data, and the following formulas help doing the same.
 Classmark = (Upper limit + Lower limit)/ 2
 Mean = Sum of the observations / Total number of observations
 Mode = The observation occurring the most frequent times
 Experimental Probability Formula: The trial counts in which the event (E) has occurred / The sum of trials
Applications of Class 9 Maths Formulas
Class 9 Maths formulas are applied in various fields. Let us see how these formulas play a role in our everyday life.
 Mathematics is ingrained in our daily lives, starting from the measurements in the kitchen to any transaction done in the shop, numbers play an important role in almost all walks of life. A proper understanding of numbers can help students in their money management too. Hence, an understanding of the number system is one of the important skills to learn for not only higher math topics but also for life in general.
 Shapes are everywhere around us. Hence, the study of geometry formulas helps us identify and solve real life problems occurring while analytically analyzing them. Whether it is to decide how much paint will be required to paint a hall, or how many bricks are required to construct a wall, class 9 maths formulas help with this real life problem solving.
 Data is everywhere and it can give amazing insights when analyzed properly. The statistics and probability formulas class 9 help in making sense of data and derive logical conclusions with it.
Tips to Memorize Class 9 Maths Formulas
 To get a good grasp on the class 9 maths formulas it is essential to use them through a variety of problems. The more the students will practice, the easier it will become to memorize these formulas on their fingertips.
 The students can get their hands on the formula images from online resources. They can set these as screensaver or wallpaper on their digital devices. In this way whenever they will use their device, they will be prompted to have a look at the formulas throughout the day resulting in a quick revision.
 The students can study with their friends which will not only help them in clearing out their doubts with each other but can make learning easy through the sharing of ideas.
Class 9 Maths Formulas Examples
Example 1: Simplify the following expression: (3 + √7)(3  √7)
Solution: Using the formula, (a + b)(a  b) = a^{2}  b^{2}
We can solve it as (3 + √7)(3  √7) = 9  7 = 2
Example 2 : A school building is to be supported using cylindrical pillars. If the height of the pillars = 10 m and radius of the pillar = 20 cm, how much concrete is needed to make 7 cylindrical pillars?
Solution: To know how much concrete is needed we need to find the volume of a cylinder and then multiply it with the number of cylinders needed.
We know that the volume of cylinder = πr^{2}h
so, substituting the value of radius = 0.2 m and height = 10 m we get,
= 22/7 × 0.2 × 0.2 × 10
= 8.8 / 7 = 1.257 m^{3}
Since 7 pillars are needed, the net concrete needed is,
8.8/7× 7 = 8.8 m^{3}
Students can download the printable Maths Formulas Class 9 sheet from below:
FAQs on Class 9 Maths Formulas
What are the Important Formulas for Class 9 Maths?
Class 9 math includes topics of Number System, Polynomials in algebra, Solid Geometry, Statistics and Probability. Some of the important formulas from these topics can be seen below:

(a + b) (a  b) = a^{2}  b^{2}
 (a + b)^{2} = a^{2} + 2ab + b^{2}
 (a  b)^{3} = a^{3}  b^{3}  3ab(a  b)
 Curved Surface Area of a Cone = 1 /2 × l × 2πr = πrl, ‘l’ = √(r^{2} + h^{2})
 Volume of a Cone = (1 / 3 )πr^{2}h
 Volume of a Sphere = (4/3) πr^{3}
 Volume of a Hemisphere = (2/3) πr^{3}
 Mean = Sum of the observations / Total number of observations
 Experimental Probability Formula: The trial counts in which the event (E) has occurred / The sum of trials
What are the Basic Formulas in Class 9 Maths?
The basic formulas in class 9 maths are from the topics of number system, algebra, geometry, statistics and probability. Remembering the basic entities from the Number System will help the students understand the rational and irrational numbers better. The expansion formulas of polynomials are helpful in finding the roots of equations. In geometry, it is important that the students remember the basic formulas of finding area and volume of different shapes and objects.
What are the important formulas covered in class 9 Algebra?
The important formulas covered in class 9 algebra help in demonstrating the difference between linear, quadratic, and cubic polynomials. Apart from the basic factorization formulas of polynomials as mentioned below, the students are advised to revise the important concepts of the Remainder theorem and the Factor theorem, that help identify the factors of a polynomial.
 (a + b) (a  b) = a^{2}  b^{2}
 (a + b)^{2} = a^{2} + 2ab + b^{2}
 (a  b)^{3} = a^{3}  b^{3}  3ab(a  b)
How many formulas are there in Class 9 Maths?
There are around 30 important class 9 maths formulas which, if learned well, can help the students in solving a lot of problems because usually most of the other formulas are derived from these basic ones. If we see how many formulas are there in each of the topics in class 9 maths then it would be as follows:
 The number system has 5 basic entities which helps students understand the relationship of rational and irrational numbers.
 In algebra, the major 5 significant formulas explain the concept of factorization, which is helpful throughout the study of algebra to facilitate finding the roots of equations.
 The surface area and volume segment has around 15 formulas covering the dimensions of cuboid, sphere, cylinder and cones.
 Statistics and probability has 5 simple formulas that help in statistical analysis and predictability of events in probability.
How can I Memorize Class 9 Maths formulas?
The best way to remember the class 9 maths formulas is to practice the problems based on them. This not only helps in understanding the usage and the appropriate relevance of all the formulas but also helps avoiding the unnecessary burden of mugging them up.
The students can also take the help of digital notes available online. They can save the formula sheet as their mobile screensaver or desktop wallpaper. This will ensure that everytime they use their mobile or laptop, the formula wallpaper will remind them to have a quick revision throughout the day.
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