Respuesta :

AL2006

Well,  625  is  5 x 5 x 5 x 5 .

So that would be:

(5)⁴

5 x (5)³

(5)² x (5)²

And you could even go the other way if you want to get silly:

(5)⁵ x (5)⁻¹

(5)⁶ x (5)⁻²
.
.
etc.