One question about calculate problems with pH?

I did an experiment, and it showed that the pH increased from 7.45 to 10.91, so it meant that the pH change is 3.46. Now I need to calculate the FOLD CHANGE IN H+ CONCENTRATION, but I don't know the formula to calculate it. Can you please show me how to calculate this value?One question about calculate problems with pH?
the rule is : pH = - Log [H+] where [H+] is H+ CONCENTRATION



So [H+] = 10^( - pH)



Let [H+]i be H+ CONCENTRATION when pHi =7.45



and Let [H+]f be H+ CONCENTRATION when pHf =7.45



So when [H+]i = 3.548 * 10^-8 mol/L and [H+]f = 1.230 * 10^-11 mol/L



I guess u know how to do the rest.One question about calculate problems with pH?
pH = -log[H+]



which means you do 10^-3.46