The remainder, when $5^{60}$ is divided by 7, is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 1 **
Compute $5^{60} \bmod 7$.
Since $5 \equiv -2 \pmod{7}$,
$5^{60} \equiv (-2)^{60} \pmod{7}$
$(-2)^{60} = 2^{60}$ (positive).
Now use the cycle of $2^{n} \pmod{7}$:
$2^{1}\equiv 2$
$2^{2}\equiv 4$
$2^{3}\equiv 8\equiv 1$
Cycle length is $3$.
$60 \bmod 3 = 0$
Therefore:
$2^{60} \equiv 2^{0} \equiv 1 \pmod{7}$
Remainder = $1$