Was just wondering: when calculating the pH and you get a value like 2.958607315 how many decimal places would you round this up to? Or would the pH simply be 3?
Surely it depends on the accuracy of your H+ molarity? For most practical purposes, you'll do it to 2 d.p. I guess, but it does depend on how accurately you know your H+ molarity.
remember this.... 3 is the magic number, so always do everything to 3 significant figures unless otherwise instructed or your doing analytical work which requires more accuracy..
I've always gone for the 3 sig figs rule. Besides, you won't be penalised for having 2.96if the required answer was 3, but you will be penalised if you put 3 instead of 2.96.