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A to Z of Excel Functions: the ISNUMBER Function

21 June 2021

Welcome back to our regular A to Z of Excel Functions blog.  Today we look at the ISNUMBER function.

The ISNUMBER function

At the time of writing, there are 12 IS functions, i.e. functions that give rise to a TRUE or FALSE value depending upon whether a certain condition is met:

  1. ISBLANK(reference): checks whether the reference is to an empty cell

  2. ISERR(value): checks whether the value is an error (e.g. #REF!, #DIV/0!, #NULL!).  This check specifically excludes #N/A

  3. ISERROR(value): checks whether the value is an error (e.g. #REF!, #DIV/0!, #NULL!).  This is probably the most commonly used of these functions in financial modelling

  4. ISEVEN(number): checks to see if the number is even

  5. ISFORMULA(reference): checks to see whether the reference is to a cell containing a formula

  6. ISLOGICAL(value): checks to see whether the value is a logical (TRUE or FALSE) value

  7. ISNA(value): checks to see whether the value is #N/A.  This gives us the rather crude identity ISERR + ISNA = ISERROR

  8. ISNONTEXT(value):  checks whether the value is not text (N.B. blank cells are not text)

  9. ISNUMBER(value): checks whether the value is a number

  10. ISODD(number): checks to see if the number is odd.  Personally, I find the number 46 very odd, but Excel doesn’t

  11. ISREF(value): checks whether the value is a reference

  12. ISTEXT(value): checks whether the value is text.

As stated above, the ISNUMBER function checks to see whether the value is a number.  It has the following syntax:

ISNUMBER(value)

The ISNUMBER function has the following argument:

  • value: this is required and represents the value for which you wish to determine whether it is a number. 

It should be further noted that:

  • if value is not a valid data type, such as a defined name that is not a reference, ISNUMBER returns the #VALUE! error value.

Please see my example below:

We’ll continue our A to Z of Excel Functions soon.  Keep checking back – there’s a new blog post every business day.

A full page of the function articles can be found here.

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