The atomic mass of Np-237 is 237.0481 u. What is the binding energy of Np-237? I did it like this but got the wrong answer: mass defect = 93(1.0073) + 144(1.0087) - 237.0481 = 1.8836amu 1.8836 amu * 931.5MeV/1amu = 1754MeV The correct answer is 1802MeV, can someone please explain why what I did was wrong?