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

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Answer: Option D

Explanation:

When a number is divided by 5 and we get a remainder of 3, it means the number can be expressed as:

Number = 5k + 3

where "k" is an integer.

Now, let's find the square of this number:

(Number)^2 = (5k + 3)^2

Expanding this expression:

(Number)^2 = 25k^2 + 30k + 9

Now, let's consider this expression modulo 5 to find the remainder when the square of the number is divided by 5.

25k^2 is divisible by 5, so it leaves no remainder.

30k is also divisible by 5, so it leaves no remainder.

Finally, 9 divided by 5 leaves a remainder of 4.

So, the remainder when the square of this number is divided by 5 is 4.

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