A number when divided by 5 leaves a remainder 3 What is the remainder when the square of this number...........

Quantitative Aptitude ( CCS) Number System

A number when divided by 5 leaves a remainder 3. What is the remainder when the square of this number is divided by 5?

If the number divided by 5 leaves remainder 2, then let the number be 5x + 2.
Squaring 5x + 2,
(5x + 2)²

= 25x² + 20x + 4

= 5 (5x² + 4x) + 4
∴ The square of the number divided by 5 leaves remainder 4.

Hence, option 1 is the correct answer.

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