To go from grams to atoms you first need to convert to moles. To convert to moles you divide the number of grams by the molar mass of calcium which is about 12. So dividing 12 by 12 gives you 1. So you have 1 mole of calcium. Then you convert to atoms by multiplying by Avogadro's number, which is 6.02 x 10^23. Now 1 x 6.02 x 10^23 = 6.02 x 10^23. Your answer should be 6.02 x 10^23 atoms.
