Closing charge is not enough for a reaction ledger to pass. In this toy check,
the scaled charge matches at 3 on both sides, but the scaled baryon number falls
from 3 to 0, so the reaction is rejected; real audits also depend on event
reconstruction, missing particles, background models, and uncertainty.
A reaction may close charge and still fail another ledger. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Charge alone is not enough
The input scaled charge is 3 and the output scaled charge is also 3.
3=3
The baryon ledger rejects the reaction
The input scaled baryon number is 3 while the output scaled baryon number is 0.