# What is the greatest perfect square that is a factor of 7?

The only integer factors of $7$ are $\pm 1$ and $\pm 7$. Of these the only one that is a perfect square is $1$.
$7$ is prime, so it's only factors are $\pm 1$ and $\pm 7$.
Of these, the only number that is a perfect square is $1 = {1}^{2}$