Remainders

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

  1. 0
  2. 1
  3. 2
  4. 4

Answer

Any number when divided by 5 leaves remainder 3 will be of type: 5k + 3

Square of Number = (5k + 3)2 = 25k2 + 30k + 9

When this square is divided by 5, remainder will be same as the remainder when 9 is divided by 5.

Hence, 4 is the remainder.

The correct option is D.