1. The problem statement, all variables and given/known data The uranium isotope 235U captures a neutron and undergoes fission to produce 93Rb and 141Cs. Calculate the energy released in this process. The nuclear masses of the relevant isotopes are 235U 235.0439u, 93Rb 92.9217u, 141Cs 140.9195u 2. Relevant equations 3. The attempt at a solution The answer is given as I realise the quantity of 1.0087 is the mass of neutron divided by one unified atomic mass unit. So that's (1.67493 x 10^-27) / (1.66 x 10^-27). Also, the 2.10087 number is simply double this. How have the 235.0439, 92.921712 & 140.91949 values been calculated? I know it's to do with E=Mc^2 Thank you.