Solution
= Solution
Modulo seven, $19\equiv-2$ and $(-2)^3=-8\equiv-1$. Therefore $19^9\equiv(-1)^3\equiv-1\equiv6\pmod7$. The remainder is \b[$6$], using <modular exponentiation>.
= Solution
Modulo seven, $19\equiv-2$ and $(-2)^3=-8\equiv-1$. Therefore $19^9\equiv(-1)^3\equiv-1\equiv6\pmod7$. The remainder is \b[$6$], using <modular exponentiation>.