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Question

Question: If 7<sup>103</sup> is divided by 25 then find the remainder –...

If 7103 is divided by 25 then find the remainder –

A

1

B

7

C

10

D

18

Answer

18

Explanation

Solution

Since 7103 = 7(49)51 = 7(50 – 1)51

= 7 {505151C1 5050 + 51C2 5049 – ....–1}

=7{505151C1 5050+51C25049 –...} – 7+18– 18

= 7 (505151C1 5050 + 51C2 5049 – ....) – 25 + 18