Where mistakes hide.
THE MOST COMMON ERRORS
Ranges that do not include all the data Formulas copied without adjusting references A row inserted outside a formula's range Text stored as numbers, or numbers as text Hidden rows excluded from a filtered view but included in a total
WHY THEY MATTER
Spreadsheet errors are silent and confident.
WHAT TO DO
Check totals against a known figure Check the row count Check the range each formula covers
THE KNOWN FIGURE CHECK
Compare your spreadsheet total against the source system total.
Always. It catches most errors immediately.
WHAT ELSE TO CHECK
That sorting did not separate related columns That filtering is not hiding records from a calculation That dates are genuinely dates
THE SORTING ERROR
Sorting one column without the others destroys the data irreversibly.
WHAT TO DO BEFORE SORTING
Select everything, or use a table.
WHAT TO AVOID
Working directly on the only copy Sharing a file several people edit without control
WHAT TO BUILD IN
A total that must match, visible on the sheet.
