From the periodic table, you will find that:
mass of Cl = 35.453 grams
mass of Na = 22.989769
Now, since NaCl is formed from the combination of one mole of sodium from one mole of chlorine, therefore, the molar mass of NaCl can be calculated as followed:
molar mass of NaCl = 35.453 + 22.989769 = 58.442769 gram/mole