Divide 625 by 5 and you get 125, that is, 625 = 5*125

Divide 125 by 5 and you get 25, that is, 125 = 5*25

Divide 25 by 5 and you get 5, that is, 25 = 5*5

Now lets go back:

625 = 5*125 = 5*(5*25) = 5*(5*(5*5))

According to the associative property of multiplication, the product of three or more numbers remains the same regardless of how the numbers are grouped, so:

625 = (5*5)*(5*5) = (5^2)*(5^2) = (5^2)^2 = 5^(2*2) = 5^4 = 5*5*5*5