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?

Question

Accepted Answer

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.

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