Where do these tiny maths error come from?

To fix this I simple use the ROUND function to limit the result to 2 decimal places and remove the error.

The sum of the round values are differant than the original data.

e.g.

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So you get a differance of 0.0024

Regarding the "why?", the floating point error in Excel is well-documented. Here's a link you might find useful: https://docs.microsoft.com/en-us/off...ccurate-result

Being aware of it and mitigating it in the way explained in post #2 will save you a lot of headaches.

This is due to the fact that; when Excel stores a number in memory, it is converted to a corresponding binary number in order to save space in memory and for increasing the speed of calculations.

So, you will have to remember this fact especially when you are comparing values of two cells such as in formulas for custom formatting.

Therefore; you have to round the numbers before comparing or accept a relatively small difference such as "0.0001" or so...

@rebecacamp

Welcome to the forum.

Be aware that making ten pointless posts simply raises our suspicion about your motive for being here, so I have my eye on you. Please start your own thread if you have a genuine question. Thanks.