The rule for an exponent raised to another exponent is:
(a^b)^c is equal to a^(b*c) so in this case:
(6^3)^(-3) is equal to:
6^(-9) which is
1/(6^9) which is:
1/10077696
What you described is what happens when you multiply two similar bases with exponents, for example
(a^b)(a^c)=a^(b+c) so if your problem was:
(6^3)(6^-3) then yes it would be equal to:
6^(3-3)
6^0
1
So keep those rules in mind...
(a^b)(a^c)=a^(b+c)
and
(a^b)^c=a^(b*c)
