Leaked shots are not allowed to vanish just because they fall outside the zero/one readout ledger. Here 20 leaked shots are carried separately, and the observed 52 zero reads plus 28 one reads return to the prepared total only when the 20 leaked shots are added back. Real leakage accounting depends on detector thresholds, classification rules, loss channels, repeated shots, and uncertainty.
Leaked shots remain visible as a separate budget line. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Leaked shots are carried outside readout
The leakage stage carries 20 leaked shots outside the zero and one readout ledger.
Nleaked=20
Observed plus leaked closes the prepared budget
Observed reads are 52 zero and 28 one. With 20 leaked shots, the total returns to 100.