CBSE · Class 8 · Mathematics · Chapter 6

Squares and
Square Roots

Complete chapter resources for CBSE Class 8 Maths — topic breakdown, key properties, sample questions, previous year board questions, and instant AI question paper generation.

4Topics
4–6Board marks
8Sample questions
3PYQ included

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Key Concepts — Chapter 6
  • Perfect square: n² where n is a natural number
  • Square root (√): √(a²) = a, a ≥ 0
  • Pythagorean triplet: (2m, m²−1, m²+1), m > 1
  • Sum of first n odds: 1+3+5+...+(2n−1) = n²
  • Unit-digit rule: perfect squares end in 0,1,4,5,6,9 only
  • Long division: pairs of digits from right → quotient digit by digit

What this chapter covers

Chapter 6 introduces square numbers — natural numbers that are squares of other natural numbers — and explores their properties: the unit-digit pattern (squares end only in 0, 1, 4, 5, 6, or 9), the fact that between consecutive squares n² and (n+1)² there are exactly 2n non-square numbers, and the elegant identity that the sum of the first n odd natural numbers equals n². Students also learn to generate Pythagorean triplets using the formula (2m, m²−1, m²+1) for any natural number m > 1.

The chapter teaches two methods to find the square root of a number. The prime factorisation method works when the number can be neatly expressed as a product of prime pairs — students group primes in twos and multiply one from each pair. The long division method applies to any positive integer and to decimal numbers; it is the standard method for numbers where prime factorisation is tedious and for finding square roots to a specified number of decimal places.

Estimation of square roots without a calculator is another key skill — identifying the two consecutive perfect squares between which a given number lies, then narrowing in. Board questions in Class 8 and subsequent classes regularly test all these methods, and understanding square roots deeply is a prerequisite for the Pythagorean theorem, irrational numbers (Class 9), and quadratic equations (Class 10).

What's inside Chapter 6

As per NCERT Class 8 Mathematics (CBSE syllabus)

Topic 1
Properties of Square Numbers
Unit-digit patterns of perfect squares. Relationship between consecutive squares: 2n non-square numbers between n² and (n+1)². Sum of first n odd numbers = n². Pythagorean triplets from (2m, m²−1, m²+1).
Topic 2
Interesting Patterns
Adding triangular numbers to get square numbers. Square of a number as the sum of two consecutive triangular numbers. Patterns with 1, 11, 111 and with numbers ending in 5. Visual square-dot arrays.
Topic 3
Finding Square Roots — Prime Factorisation
Expressing a number as a product of primes, pairing identical primes, and multiplying one from each pair. Checking whether a number is a perfect square by verifying all primes appear an even number of times.
Topic 4
Finding Square Roots — Long Division Method
Grouping digits in pairs from the decimal point. Successive subtraction-and-doubling procedure. Extending to decimals and fractions. Estimating square roots to a specified number of decimal places.

How this chapter fits in

Useful for setting question difficulty and cross-chapter papers.

Builds on
Ch 1 · Rational Numbers
Properties of multiplication and division of integers
Class 7 · Exponents
Square as exponent 2; prime factorisation skills
Chapter 6 Squares &
Square Roots
Leads to
Ch 7 · Cubes and Cube Roots
Extends the same prime-pairing logic to groups of three
Class 9 · Number Systems
Irrational numbers, surds, and the real number line

Marks & question-type breakdown

Typical pattern based on CBSE Class 8 school and periodic assessment papers.

Question type Marks Typical count What's usually tested
MCQ / Objective 1 1–2 Identify perfect squares, unit-digit rule, Pythagorean triplet verification
Very Short Answer 1–2 1 Square root by prime factorisation for a given number
Short Answer 3 1 Long division method to 2 decimal places, or generating a Pythagorean triplet
Long Answer / Word Problem 4–5 0–1 Area/length problem requiring square root, or least number to be added/subtracted
Total (approximate) 4–6 3–4 Weightage varies across paper sets and terms

8 sample questions — generated by MarksZen AI

Aligned to CBSE Class 8 Maths Chapter 6. Covers all question types across Easy, Medium, and Hard difficulty.

Q1 Easy 1 mark MCQ
Which of the following numbers is a perfect square? (a) 72 (b) 128 (c) 169 (d) 200
Q2 Easy 1 mark MCQ
How many non-perfect-square numbers lie between 15² and 16²? (a) 28 (b) 30 (c) 31 (d) 32
Q3 Easy 2 marks Short Answer
Find the square root of 1764 using the prime factorisation method.
Q4 Medium 2 marks Short Answer
Write a Pythagorean triplet whose smallest member is 14.
Q5 Medium 3 marks Short Answer
Find the smallest number that must be subtracted from 9748 so that the result is a perfect square. Also find the square root of the resulting perfect square.
Q6 Medium 3 marks Short Answer
Find √(5.29) using the long division method.
Q7 Hard 4 marks Word Problem
A school arranged 2025 students in rows for a march-past such that the number of students in each row equals the number of rows. How many students were there in each row? If 41 more students join, what is the minimum number of additional rows needed to maintain the same square arrangement?
Q8 Hard 5 marks Word Problem
The area of a square field is 6241 m². A farmer wants to fence the field with barbed wire. (i) Find the side of the square field. (ii) Find the perimeter of the field. (iii) If wire costs ₹15 per metre and the farmer wants to put 3 rounds of fencing, find the total cost.
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From CBSE school examinations

Representative questions from Class 8 annual and periodic assessment papers — Squares and Square Roots chapter.

Board 20222 marks
Find the square root of 4096 by the prime factorisation method. (CBSE Class 8 Annual 2022)
Board 20233 marks
Find the least number that must be added to 1300 to make it a perfect square. Find the square root of the perfect square so obtained. (CBSE Class 8 PA-2 2023)
Board 20203 marks
Using the long division method, find the square root of 1024. Also verify your answer using prime factorisation. (CBSE Class 8 Annual 2020)

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Questions teachers ask

How many marks does Squares and Square Roots carry in the CBSE Class 8 Maths exam? +
Typically 4–6 marks across 2–3 questions — one 1-mark objective question on identifying perfect squares or Pythagorean triplets, one 2-mark short answer on finding square roots by prime factorisation, and one 3-mark question on the long division method or word problem. The chapter carries consistent weight in school exams and periodic assessments.
What is the fastest method to find the square root in exams — prime factorisation or long division? +
Prime factorisation is faster and simpler for perfect squares with small or recognisable factors (e.g., 441, 1764). The long division method is the only reliable approach for larger numbers, non-perfect-square decimals, or when the problem explicitly asks for an approximation. Students should master both: prime factorisation for speed in MCQs, long division for 3–4 mark questions.
How do you check whether a given number is a perfect square without fully factorising it? +
Apply the unit-digit rule: a perfect square can only end in 0, 1, 4, 5, 6, or 9. Numbers ending in 2, 3, 7, or 8 are never perfect squares — a common 1-mark MCQ trick. For borderline cases (e.g., 196, 225), verify that the prime factorisation pairs up completely, with every prime appearing an even number of times.
What are Pythagorean triplets and how are they generated from this chapter? +
A Pythagorean triplet (a, b, c) satisfies a² + b² = c². The NCERT formula for generating triplets is: for any natural number m > 1, the triplet is (2m, m²−1, m²+1). For example, m = 2 gives (4, 3, 5). Board questions either ask students to verify a given triplet or to generate one using a specified value of m. These are predictable 1–2 mark questions.
How do I generate a custom question paper for Squares and Square Roots using MarksZen? +
Sign up for a free MarksZen account, choose CBSE Class 8 Mathematics, select Chapter 6 (Squares and Square Roots), set your preferred question-type mix (MCQ, short answer, word problem) and total marks — the AI generates a complete board-aligned paper with answer key in under 2 minutes, ready for PDF export.