Hi, could someone please try and figure out where I'm going wrong here. This is a calculation for a collision between 2 helium-3 nuclei which produces 1 helium-4 nucleus and 2 protons. The numbers are taken from wikipedia. Mass before = 2(3.0160293 u) = 6.0320586 u Mass after = 1 helium-4 nucleus + 2 protons = 4.002602 + 2(1.00727646677) = 6.017154932 u 6.0320586 - 6.017154932 = 0.014903668 u 1 u = 931.494 MeV 0.014903668 * 931.494 = 13.88267732 MeV, and yet wiki says it's just 12.9 MeV. Can anyone see the problem? I tried another calculation similar to this for another equation on wikipedia and got almost the exact answer that they had, but this is just a bit off.