The remainder, when $5^{60}$ is divided by 7, is |
5 1 2 3 |
1 |
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 = $1$ |