Three rows show when baryon number is kept, lost, or canceled. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Keeping a proton keeps baryon number
Baryon ledger starts at 3 and ends at 3; accepted bit is 1.
3→3,a=1
Replacing a proton loses baryon number
Baryon ledger starts at 3 and ends at 0; accepted bit is 0.
3→0,a=0
Matter and antimatter can cancel baryon number
Baryon ledger starts at 0 and ends at 0; accepted bit is 1.