Learn Class 8 Math - Squares and Square Roots

Introduction to Square Numbers

A natural number m with the formula n/2 is a square number if n is also a natural number.

Example: 1, 4, 9, 16, and 25.

Calculating the square of a number

If n is a number, then its square can be expressed as n * n = n square

E.g. The square of six is equal to 6*6 = 36

Using identity to find the square of a number

You can easily find the squares of numbers with two or more digits by summing two numbers.

For example: 23 square = (20 + 3) 2 = 20 (20+3)+3(20+3) = 20 square+20×3 + 20×3 + 32 = 400 + 60 + 60 + 9 = 529

Properties of the Square Number:

  • There's no perfect square if the number ends in 2, 3, 7, or 8.
  • Zeros on an odd digit don't make a perfect square.
  • Even numbers squared equal an even number.
  • When a number is odd, its square is odd.
  • Squares of proper fractions are smaller than their fractional parts.
  • Each natural number n has the formula [(n + 1)2 - n2} = {(n + 1) + n}.
  • Natural number n 2 = sum of first n odd numbers.
  • The triplet consisting of m, n, p is called a Pythagorean triplet if (m2 + n2) = p2.
  • The Pythagorean triplet is formed by (2m, m2 – 1, m2 + 1) for every natural number m > 1.

Squares and Square Roots Sample Questions for Class 8

Question 1

Find the smallest number to be multiplied to make 1746 a perfect square.
A. 9
B. 2
C. 97
D. 194

Question 2

There are 5800 students to be arranged in rows and columns. Number of rows and columns are equal. How many children are in each row ? How many children are left out ?
A. 77,23
B. 88,20
C. 76,24
D. 80,13

Question 3

Find pythagorean triplet of 32.
A. 32, 255 , 257
B. 15, 16 , 17
C. 32, 33,34
D. 254, 255,257

Question 4

Which of the following smallest square number is divisible by 2,3 and 6?
A. 576
B. 3600
C. 900
D. 324

Question 5

Raghav bought 20kg of wheat at ₹32 per kg. The price was reduced by 10% per kg next month. How much more wheat can he buy with same amount?
A. 2.2 kg
B. 4 kg
C. 3.6 kg
D. 1.7 kg