Finding the Molar Mass

To find the molar mass you add the atomic mass of atoms


For example if I wanted to find out the atomic mass of P2O3 


I would first find P on the periodic table of elements. 
P's mass is 30.97, and I round this to 31
Because it is P2 I multiply it by 2 to get 62


I then find O on the periodic table
O's mass is 16.00
Because it is O3 I multiply it by 3 to get 48


I then add 62 and 48 to get 110 as the atomic mass for P2O3