# 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:

**ISBLANK(reference):**checks whether the**reference**is to an empty cell**ISERR(value):**checks whether the**value**is an error (*e.g. #REF!, #DIV/0!, #NULL!*). This check specifically excludes*#N/A***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**ISEVEN(number):**checks to see if the**number**is even**ISFORMULA(reference):**checks to see whether the**reference**is to a cell containing a formula**ISLOGICAL(value):**checks to see whether the**value**is a logical (TRUE or FALSE) value**ISNA(value):**checks to see whether the**value**is*#N/A*. This gives us the rather crude identity**ISERR + ISNA = ISERROR****ISNONTEXT(value):**checks whether the**value**is not text (*N.B.*blank cells are not text)**ISNUMBER(value):**checks whether the**value**is a number**ISODD(number):**checks to see if the**number**is odd. Personally, I find the number 46 very odd, but Excel doesn’t**ISREF(value):**checks whether the**value**is a reference**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.*