Spreadsheet Data-Cleanup Checklist

Produce a safe sequence for finding duplicates, invalid formats, missing values and formula risks before analysis.

Create produce a safe sequence for finding duplicates, invalid formats, missing values and formula risks before analysis.

Use these inputs:
- column list: [column list]
- known data issues: [known data issues]
- intended analysis: [intended analysis]

Return the finished result first. Then add a short assumptions note and three practical improvements. Do not invent facts, research, testimonials or results. If one essential detail is missing, use the safest reasonable assumption and label it instead of restarting with a long questionnaire.