On dividing a number by 5, we get 3 as remainder. What will be the remainder when the square of this number is divided by 5?

A 0

B 1

C 2

D 4

Correct Answer: Option D

Let the number be x and on dividing x by 5, we get k as quotient and 3 as remainder.

x = 5k + 3

x2 = (5k + 3)2

= (25k2 + 30k + 9)

= 5(5k2 + 6k + 1) + 4

On dividing x2 by 5, we get 4 as remainder