FIND SUCCESS 4U / PRACTICE SET 01
Three checks before you trust an AI-cleaned sales report
Version 1 / 1 November 2026

This is fabricated practice data, not a real business report.
No AI subscription, email address or upload of your own data is needed.

CHOOSE YOUR PRACTICE PATH
- Break and restore (as in the video): open the checker. AI output ALREADY
  CONTAINS THE ORIGINAL CLEANED ANSWER. Make one deliberate change at a time.
- Clean it yourself first: use sales-messy.csv and business-rules.txt BEFORE
  opening the checker. Then compare your result with the separate answer
  CSVs by line_id. Do not paste a differently ordered file into this checker.

START HERE: BREAK AND RESTORE
1. Keep sales-messy.csv unchanged. Read business-rules.txt before comparing.
2. Extract this ZIP into a folder. Open Raw-Source-Checker.xlsx in desktop Excel.
   The workbook already contains the supplied raw data and original cleaned
   output. Do not paste the CSV over either sheet just to begin the exercise.
3. Read Guide, then open Checks. The supplied comparison starts at MATCH.
   A matching comparison still leaves the missing-date records for review.
   If Excel uses Protected View, review the source before enabling editing
   in your practice copy. No macros or AI add-in are required.
4. Save a separate practice copy. Change ONE field in AI output, columns A:G,
   starting at row 7; recalculate using Formulas > Calculate Now.
5. Inspect the resulting flags, then undo/restore the edit and recalculate
   before trying another. Keep Raw unchanged throughout the exercise.
   Do not sort, insert, delete or reorder rows in Raw or AI output.

THREE SMALL TESTS
- Missing line: in AI output, clear the contents of A8:G8 (L00002). Do not
  delete the worksheet row or shift the surrounding cells. Restore it next.
- Wrong sign: change AI output!G7 from -4.99 to 4.99. Restore -4.99 next.
- Wrong month: change AI output!C8 from 2026-01-01 to 2026-02-01, preserving
  the cell's text format. Restore 2026-01-01 next.

WHERE THE CHECKS COME FROM
Source build computes its counts, categories, dates and signed cents from
Raw under the supplied rules. Checks compares those results with AI output.
The separate answer CSVs do not feed those formulas.

BOUNDS THAT MATTER
This workbook fits only this supplied fixture and row order, with capacity
for 2,000 raw and output rows (A7:G2006) and January-March reporting tables.
Keep identifiers, dates and the original raw CSV fields as text. Reordering,
new keys, another export or extra reporting periods require adapting the
index, ranges and rules. It is not a general-purpose CSV importer.
View the original CSV in a text editor or import every column as text.
Do not save over the raw CSV from Excel, which can change dates and IDs.
The source was tested in desktop Excel for Windows with English (Singapore)
number and date conventions. Web Excel, Mac, Sheets, Numbers, other regions
and phone spreadsheet apps have not been verified for this exercise.

The source workbook was checked in Windows Excel. For public distribution,
only editor/path and attached add-in metadata was changed; worksheet XML,
formulas, cached results, styles, tables and worksheet relationships are
byte-identical to that source. No AI add-in is attached to the public copy.
The exact public bytes opened in desktop Excel without a recovery/add-in
prompt and showed four MATCH results. This was an open check, not a repeat
of the source workbook's calculation and deliberate-change tests.
See Checker-Method.txt for the method and verification limits.

Mark your work using the separate optional answer CSV download on the
practice page. The checker itself already contains the original cleaned
answer on AI output. The starter ZIP has no separate answer-key workbook.