Can You Really Trust Your Spreadsheet…?

Every time I work on migrating a mission critical, spreadsheet based system to a custom developed system, there’s always at least one head scratching discovery. More often than not, the history of the change has been lost to the sands of time.

One discovery stands out as my favourite though…

The spreadsheet I was converting was fairly standard. I pulled out the existing data and formulas. It was going well until I started digging into the formulas related to timesheets and invoicing.

Essentially, the spreadsheet had a column of cost line items. These would be added together to calculate the invoice total. As part of testing and understanding the spreadsheet I randomly added some emoji costs to see what would break.

Turns out the answer was nothing.

No cells got angry. Some cells changed. The whole spreadsheet was happy to compute 🍎 + 4 (which is 29 as everyone knows).

Here’s the point. A spreadsheet is a great tool for smaller problems, but once they become mission critical or sufficiently complex, you should probably be considering a more robust system. A well developed piece of software will have sanity checks in place to ensure you don’t find yourself in this type of situation.