A reaction passes only when every required ledger closes. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
One reaction closes every displayed family ledger
The accepted muon case has electron-family total 0 and muon-family total 1 on both sides.
01
Another reaction closes charge but fails another ledger
The rejected proton case has scaled charge 3 on both sides, but its scaled baryon total changes from 3 to 0.