How to calculate the fold change of pH?

I did an experiment and I got the total pH change of tap water is 1.64. Then it asks for the fold change in H+ concentration. What does that mean? Do I take 10^(-1.64)? And what about the equation pH=-log[H+]? I'm a little confused, please help!How to calculate the fold change of pH?
I guess that's what they mean with fold (times).

Then, pH is nothing other than the description in powers of the concentration of H+ 10^-1 to 10^-14

So yeah the answer should be 10^-1.64, but this should be a hell of alot smaller than 43.650.