What is the molar mass of #Ca_3(PO_4)_2#?
Can you tell me the molar mass of ATOMIC calcium, phosphorus, and oxygen?
In fact you can do this, because you do have access to a Periodic Table, and the atomic masses are printed on the Table. All scientists use the Table daily to assign molecular masses.
And the atomic mass of calcium metal is
And to determine the molecular mass, all I do is appropriately sum these atomic masses: