A simple tip for when you perform calculations (SUM, SUMIFs, etc.) on a spreadsheet – add checks.
Here’s how it works –
1. Keep the “master” data separate from the calculations – this ensures you never pollute the original data.
2. Once you complete the calculations, ensure you periodically check your math. You can do this by using “=”. For example, it might be =SUM(all cells in calculation)=SUM(all cells in source data)
This is harder to explain with an abstract example. So, here is an example of how you might add checks to a spreadsheet when you are attempting to split costs after a trip with friends. I’ve highlighted the check cells in yellow.
As we work through details on spreadsheets, it is easy to get small details wrong. When that happens, you can rely on these cells to immediately become “FALSE” and save you the trouble of dealing with flawed math.
Checks in spreadsheets are simple mistake detection investments that pay off in a big way.
Just as in other areas of our life.