Tutorials that end with a working spreadsheet
A tutorial here is a small job done properly: a loan schedule that balances to zero, a price lookup that finds the right row. The spreadsheet is built, recalculated in a real spreadsheet engine, and compared cell by cell against an independent computation. The file you download is the file that was checked.
Tutorials
| Tutorial | Apps | Checked |
|---|---|---|
| Build a loan amortization schedule in Excel with PMT, IPMT and PPMT A $25,000 loan at 6.5% over 5 years. Monthly payment $489.15, total interest $4,349.22, final balance $0.00. All 60 rows checked. | Excel, Sheets, LibreOffice | |
| Look up a price in Excel with INDEX and MATCH A price list where the SKU sits between the product name and the price, so VLOOKUP cannot reach left. HD-104 returns $21.50; a missing SKU returns “Not in price list”. | Excel, Sheets, LibreOffice |
How a tutorial is checked
- Build the file. The spreadsheet is built with formulas, not typed-in answers.
- Recalculate it. The file is recalculated by LibreOffice in headless mode, a real spreadsheet engine, not the tool that wrote it.
- Compare every claimed number. The recalculated values are read back and compared against an independent computation written separately in Python. A tutorial ships only when they agree.
- Attach the file. The download on the tutorial page is the file that passed the check.
Versions and measured results are listed at the top of each tutorial. The Method page has the full procedure.