Physics! Hubble constant! What is km/s-1/Mpc-1?

Not really a programming question, and I actually signed up at a physics forum and asked this question there this morning:

Calculating distance using redshift

But I'm dubious about the one reply and figured one of you geniuses must know.

What does it mean when units are specified to the power of -1? Eg:

Quote:

The value of the Hubble constant that is determined using type 1a supernovae as standard candles is H0 = 65 km s-1 Mpc-1

-1 should be superscripted in both cases.

Am I correct in asserting that the value (65) should be multiplied by 0.1 to work in a formula which uses km/s (for c) and yields Mpc? Applying the formula from (see post) yields correct answers if I do, but is out by a factor of 10 if I don't.

If anyone can rearrange that algebraically to show how those units work out that'd be :cool: I have a math inferiority complex.