Question about Modular Arithmetic I have a question about Modular Arithmetic Cryptography.

How do I calculate $(-5)^{-3}$ or $(-5)^{-4}$ (even or uneven exponent)? 

What do I have to do first here ? I can’t ignore the minus?!?
(-5)^(-x) = (-5)^((-1)*x) = ((-5)^(-1))^x

The above link also has a good "Computation" section.