(5^-3)^6

To simplify this expression, we first need to take the negative exponent into account.

Recall that for any non-zero number, x, (x^-n) = 1/(x^n).

So, (5^-3) = 1/(5^3) = 1/125.

Now, our expression becomes (1/125)^6.

To simplify further, we raise 1/125 to the power of 6:

(1/125)^6 = (1^6)/(125^6) = 1/125^6 = 1/244140625.

Therefore, (5^-3)^6 = 1/244140625.