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# RD Sharma Class 8 Chapter 4 Solutions (Cubes and Cube Roots)

RD Sharma Class 8 Maths Solutions for Chapter 4 ‘Cubes and Cube Roots’ covers all the important concepts like factorization, grouping and division method. In this chapter, you will learn what are cubes and perfect cubes, cubes of even and odd numbers and how we can find the cube root of a number. The chapter also provides word problems based on applications of cubes and cube roots.

RD Sharma Solutions for Class 8 Chapter 4 ‘Cubes and Cube Roots’ has a total of 5 exercises and 76 practice questions. These exercises have different questions like word problems, division based derivation, true and false and factorization questions. All of these questions play a great role in providing thorough revisions of the chapter and polishing your basics.

Instasolv has formulated all the answers to RD Sharma Class 8 Maths Chapter 4 in order to meet your needs for self-sufficient and stress-free learning. Our team is devoted to ensuring that you have all the resources required for engaging with the chapter. With the help of our solutions, you will no longer find the chapter confusing and will develop a strong command on the chapter along with a firm hold on the different ways of solving the problems.

## Important Topics of RD Sharma Class 8 Solutions for Chapter 4 – Cubes and Cube Roots

Cubes and Cube Roots

Since the chapter itself is named as “Cubes and Cube Roots” it will begin with an introduction to the same.  When a number is multiplied thrice with its own value, it is termed as a cube. For example, 27 is the cube of three as when 3 is multiplied by its own self thrice i.e. 3 x 3 x 3 the answer is 27. In the same scenario,  3 will be the cube root of 27.

Not only in this chapter but the concept will be utilized in other chapters from your syllabus. The chapter provides a table of cubes from 1 till 20, which must be learnt in order to simplify calculations in your future chapters and senior classes as well.

Factorization

Just like you had learnt about the method of factorization to derive square roots of a number, you will use them to find cube roots. The difference is the fact that instead of making pairs of two you will make groups of three.

You will have to find the factors of the given number and then arrange them in groups of three, in case if the numbers form a perfect group they are termed to be perfect cubes and in case if they are short of a number in the group, they do not qualify as perfect cubes.

Last Digit Detection

In this chapter, you will come across various tricks to determine the cubes or cube roots of a number. One of these tricks is to observe the last digit of the given number. The chapter has explanations for many digits like 3, 7 and 11. These tricks can help you simplify your calculations and along with saving time. They will also fetch you marks in your exams.

### Exercise Discussion of RD Sharma Solutions for Class 8 Chapter 4 – Cubes and Cube Roots

Exercise 4.1

• The first exercise of the chapter is somewhat easy in terms of the logic and calculation that is used to derive the answers in it.
• It has a total of 23 questions. The very first question has nine subparts. In this question, you are given different numbers and you are required to find the cubes of each number.
• The method used is the basic one where you just have to multiply the numbers thrice with its own value.
• There are questions where you are required to observe the given tables while some questions are pattern-based.
• The exercise also has word problems like question number 6, where you are given an equation with a variable and a set of directions according to which you have to find the cubes of the natural numbers.

Exercise 4.2

• The second exercise has 5 questions in it. The first question has three sub-parts where you have to find the cube of negative numbers.
• This exercise also has factorization-based questions where you will have to make groups of three in order to find the cube root. In case if the groups of three are not formed, the number is not a perfect cube.
• The fourth question of this exercise is a bit confusing as it deals with fractional values but with good practise you will easily be able to solve them without much confusion.

Exercise 4.3

• The third exercise has 9 questions. The questions in this exercise are a bit lengthy and require logic and analysis.
• There are word problems like question 5, where you have to factorize the number based on the conditions given and derive the answer to the question.
• Question 9 deals with the volume of a cube and is another interesting word problem from the exercise.

Exercise 4.4

• The fourth exercise comprises of questions where you have to find cube roots of decimal numbers, fractional numbers, and integers.
• There are evaluation-based questions added to the exercise along with a few questions where you are required to verify your answers along with the calculations.

Exercise 4.5

• The last exercise has 22 questions. It begins with subtraction between two cubes and you have to follow the method of factorization in order to solve this exercise.

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