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 {5051 – 51C1 5050 + 51C2 5049 – ....–1}
=7{5051 – 51C1 5050+51C25049 –...} – 7+18– 18
= 7 (5051 – 51C1 5050 + 51C2 5049 – ....) – 25 + 18