Use a scaled charge ledger so the proton's three quarks can be checked with
whole numbers. The two up quarks and one down quark contribute 2, 2, and -1 for
a total scaled charge of 3, while the three quark baryon entries close the
scaled baryon ledger; real particle identification still depends on detector
tracks, charge calibration, reconstruction cuts, and uncertainty.
A proton ledger is computed from its checked quark content. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Three quark charges sum to proton charge
The scaled charges are 2, 2, and -1; their sum is 3.
2+2+−1=3
Three quarks make one baryon ledger
Each quark contributes 1 to the scaled baryon ledger, so the total is 3.