I tried using this formula for cube rooting but it doesn't seem to work.


The value of C38 is -2.

I'm getting the following error:

Imaginary numbers are not supported in real sheets.

Shouldn't cube roots logically work without being imaginary, whether it's negative or positive?

  • Could you share the spreadsheet with us? Or another spreadsheet demonstrating the problem? Jan 21, 2014 at 8:48

2 Answers 2


I am not sure why it's not supported but you can bypass it this way:

=ROUND(IF(C38 < 0,-1*ABS(C38)^(1/3),C38^(1/3)))

That would be your formula for rounding a cube root.

  • Wow it actually works thanks :)
    – puretppc
    Jan 21, 2014 at 22:46

Use the following notation to perform these types of calculations.




I thought it was a rather odd behavior of Google Spreadsheets and therefore I started to investigate the situation.

It started by performing the calculation in the Google Calculator: enter image description here

There, the notation


was re-written to


This solves your problem immediately. Entering the last formula (with ROUND()) in Google Spreadsheets, will give you : -1. But why?


In the first reference, Dr. Math is explaining the matter in detail. Bottom line is that the calculation is returning an imaginary number, like the cube root of -1.

To avoid these calculations, the minus is simply extracted from the calculation and "added" afterwards.


  1. Dr. Math
  2. There's no bug

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