I was working at the energy released through the triplealpha process, and came to a slight problem. I worked out for Helium first, using: (2 x 1.007825u) + (2 x 1.008665u) - 4.002602u = 0.030378u which when x3 and converted gives ~84.9MeV. Doing the same for carbon, but using 12.011u for the atomic mass (as is given in most places), I end up with ~81.9MeV, when I should be getting ~92.2MeV. But when I do the same equation using 12u, I get the right answer! What's going on?