QUESTION

CSAT

Medium

Maths

Prelims 2016

If R and S are different integers both divisible by 5, then which of the following is not necessarily true?

Select an option to attempt

Explanation

Let's analyze each option: A. R – S is divisible by 5: Since both R and S are divisible by 5, their difference will also be divisible by 5. This is true.

B. R + S is divisible by 10: If R = 5 and S = 15, R + S = 20, which is divisible by 10. But if R = 5 and S = 10, R + S = 15, which is not divisible by 10. So, this is not necessarily true.

C. R × S is divisible by 25: Since both R and S are divisible by 5, their product will be divisible by 25 if both are divisible by 5 twice. But if R = 5 and S = 10, their product is 50, which is divisible by 25. So, this is true.

D. R² × S² is divisible by 5: Since both R and S are divisible by 5, their squares will also be divisible by 5. So, this is true.

Therefore, B is not necessarily true.

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