All records and amounts are fictional. Start with learner-guide.txt and the two unchanged CSVs. Keep a first attempt in discrepancy-log.csv before reading answer-key.txt. Optional offline check: put verify.py beside the CSVs and run python3 verify.py. No packages, network, paid tool or account is required. Arithmetic was checked with Decimal/integer cents and a spreadsheet formula engine; this is not a tested Excel workbook or a learner trial. No financial advice or instruction to alter real records.
