625. To do this, we can try to find a number that, when multiplied by itself three times, equals 15.625.
We can start by trying some numbers. For example, let's try 2:
$2^3 = 2 \times 2 \times 2 = 8$
That's too small, so let's try 3:
$3^3 = 3 \times 3 \times 3
Show more…