Why am I getting #NUM error in Excel when trying to input:


It works fine on Wolfram Alpha..

2 Answers 2


You need to use imaginary number functions for your equation. Excel expects real numbers for its operations; so it returns #NUM when an imaginary number is created and you didn't specify an imaginary number function.

  • Run it all the way home. Explain how to accomplish that.
    – fixer1234
    Jul 10, 2015 at 4:02
  • @fixer1234 I don't have Excel at home, so I don't know what the functions are. Maybe you could post them and I'll remove my post.
    – LDC3
    Jul 10, 2015 at 4:39

The fourth root of a negative number will be a complex (real + imaginary) number in the form: a+bi that your Excel formula is unable to manage.

You have to rewrite your formula to:


That will give you the result:


The same as Wolphram Alpha

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