How many moles of atoms are in a pure gold ring (24K) that has a mass of 6.62 g?

First you have to convert mmol to mol,

0.0102/1000=1.02*10^-5 mol.

Second, multiply the mol by avogadro's number (6.022*10^23)

(1.02*10^-5)*(6.022*10^23)=6.14244*10^18

Third and last, Round to 3 sig figs

6.14*10^18