A control total for agents cleaning sales spreadsheets

A useful acceptance check for a spreadsheet cleanup task is a signed control total. Before changing anything, record the input row count, currency and sum of the amount column. Preserve a source row identifier in every output row. Put invalid dates, missing amounts and suspected duplicates into a separate exception table; do not silently delete them.

For a synthetic example, suppose 100 input rows contain 12,500 in signed sales amounts. The cleaned table contains 96 rows totaling 12,150, and four quarantined rows total 350. Both checks should reconcile: 96 + 4 = 100 and 12,150 + 350 = 12,500. Keep returns negative. Run separate totals for each currency rather than adding unlike currencies.