Binding per nucleon is a budget check: subtract the nucleus energy from the free-nucleon total, then divide by the nucleon count. The rows show 8 joules across 4 nucleons, 18 joules across 6, and 16 joules across 8, giving per-nucleon values 2, 3, and 2. Real binding comparisons depend on measured masses, reference states, unit conversions, rounding, and uncertainty.
Free and bound energy budgets close per nucleon. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Four nucleons bind at two each
Free total 20 joules minus nucleus budget 12 joules gives binding 8 joules across 4 nucleons.
8÷4=2
Six nucleons bind at three each
Free total 30 joules minus nucleus budget 12 joules gives binding 18 joules across 6 nucleons.
18÷6=3
Eight nucleons return to two each
Free total 40 joules minus nucleus budget 24 joules gives binding 16 joules across 8 nucleons.