Worked example - is the decay Delta++ -> p + pi+ allowed? The Delta++ is a baryon (uuu) with charge +2, mass 1232 MeV/c^2. Step 1, baryon number: Delta++ has B = +1; proton has B = +1, pion pi+ has B = 0. Total after: 1 + 0 = 1. Step 2, charge: +2 -> +1 (proton) + 1 (pi+) = +2. Step 3, energy: the Delta++ mass (1232 MeV/c^2) exceeds m_p + m_pi = 938 + 140 = 1078 MeV/c^2, so there is enough rest energy. All checks pass - the decay is allowed, and indeed the Delta++ decays this way via the strong force in about 10^-23 s. Contrast with p -> e+ + pi0: baryon number +1 -> 0 + 0 violates B conservation, so the proton is stable.