CALCULATE THE BINDING ENERGY OF AN ALPHA PARTICLE 
The mass of 2 protons = 2 x 1.007825 amu

The mass of 2 neutrons = 2 x 1.008665 amu

Total Mass = 4.032981 amu

The actual mass, as measured by a mass spectrometer, is 4.002800 amu.

Delta m = 4.032981-4.002800 = 0.030180

NOW, 

Binding energy = 0.030180 * 931 = 28.097 Which is the answer,,,,
BUT,

The Formua to find B.E is delta m . c^2 
so the ans should be like this , 
= 0.030180 * (3*10^8)^2.... am I right ?