You are starting with 70.0 grams of Potassium Hydroxide (KOH) and you need to convert that to moles of KOH, which means you need to do some Dimensional Analysis. First off, you need the mass of KOH, which is 39.10 (K) + 16.00 (O) + 1.008 (H) grams per mole. Add that together and you get 56.108 grams per mole. Now you can set up your conversion:
70.0 g KOH * mol KOH/56.108 g KOH.
When you divide 70.0 by 56.108, you get 1.25 moles KOH because the grams cancel and you're left with just moles. 1.25 is rounded to three significant figures.
