In order to calculate the pH and concentration of hydrogen ions we will usually have two formulas:
pH = -log [H+], this one for pH, but in our question we want to find out what is the concentration of H+, so let's modify the pH equation:
[H+] = 10^-pH
[H+] = 10^-13
[H+] = 1*10^-13, this is the concentration of hydrogen ions for Bleach