8. The product of all the factors of $5^{15}$ is $5^{P}$. What is the value of $P$ ?
SolUTion
120

The factors of $5^{15}$ are $5^{0}, 5^{1}, 5^{2}, \cdots, 5^{15}$.
Their product is $5^{1+2+\cdots+15}=5^{120}$.