Question

The remainder when 7¹⁰³ is divided by 25 is –

• A. 0
• B. 18
• C. 9
• D. None of these

Answer 1

Answer: (B)

18

Answer 2

$\frac{7^{103}}{25}$ = $\frac{7\lbrack 49\rbrack^{51}}{25}$ = $\frac{7\lbrack 50–1\rbrack^{51}}{25}$

= $\frac{7\lbrack 25k–1\rbrack}{25}$

= $\frac{25(k^{1})–7 + 25–25}{25}$

=$\frac{25(k^{1}–1) + 18}{25}$

Ž Remainder = 18