How many grams of Magnesium are in 3 moles of Magnesium (Mg)?

To find out how many grams of Magnesium there are in 3 moles of Mg we need to us its atomic mass: 24.3 g/mol
So:
24.3 g of Mg ---- 1 mol of Mg
x g of Mg ---- 3 moles of Mg
x = 72.9 g of Mg
Answer: 72.9 g of Mg