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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 ?

0
1
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4
Explanation:

Let the number be $ x $ and on dividing $ x $ by 5, we get $ k $ as quotient and 3 as remainder.

$\therefore$    $ x $ = 5k + 3

$\Rightarrow$    $ x $2 = (5k + 3)2

   = (25 k 2 + 30$ k $ + 9)

   = 5(5 k 2 + 6$ k $ + 1) + 4

$\therefore$On dividing $ x $2 by 5, we get 4 as remainder.

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