pH of a base ....
We know its a base because the hydroxide ion concentration must be greater than the hydrogen ion concentration.
pH = -log[H+] ............. and ............ Kw = [H+][OH-]
pH = -log(Kw / [OH-])
pH = -log(1.00x10^-14 / 1.8x10^-3) = 11.26
When taking the log of a number, only the digits to the right of the decimal reflect the precision in the original number. Since the OH- concentration was given to two significant digits, the pH can be expressed to only two significant digits, and those are to the right of the decimal place.
Back in the olden days, when I started learning chemistry, no one used pOH. There was no need, and really there is still no need. You'll never see a pOH meter.