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COMEDK · Maths · 7. Binomial Theorem

The remainder when \(7^{103}\) is divided by \(25\) is

  1. A \(7\)
  2. B \(18\)
  3. C \(1\)
  4. D \(-1\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(18\)

Step-by-step Solution

Detailed explanation

We need to find the remainder when \(7^{103}\) is divided by \(25\). We can write \(7^{103}\) as \(7 \cdot 7^{102} = 7 \cdot (7^2)^{51}\). We know that \(7^2 = 49 \equiv -1 \pmod{25}\). Raising both sides to the power of \(51\), we get: \((7^2)^{51} \equiv (-1)^{51} \pmod{25}\)…