How ISNUMBER works in Excel? Best ISNUMBER examples

How ISNUMBER works in Excel? Best ISNUMBER examples

One of my favorite Excel functions when working with data validation and logical testing is ISNUMBER. It’s simple yet powerful, allowing me to check whether a given value is a number. Whether I’m cleaning data, building error-proof formulas, or automating processes, ISNUMBER plays a crucial role. Let’s explore this function in detail.

What is ISNUMBER in Excel?

ISNUMBER is a built-in function in Excel that checks if a given value is a number. It returns TRUE if the value is a number and FALSE otherwise.

The syntax is straightforward:

=ISNUMBER(value)

Arguments:

  • value – The value or cell reference to check.

How ISNUMBER Works in Excel?

ISNUMBER evaluates whether a value is numeric. It considers integers, decimals, and even numbers formatted as percentages as valid numbers.

Here’s a simple example:

Cell Value Formula Result
A1 42 =ISNUMBER(A1) TRUE
A2 Text =ISNUMBER(A2) FALSE
A3 3.14 =ISNUMBER(A3) TRUE
A4 25% =ISNUMBER(A4) TRUE

Best ISNUMBER Examples

1. Identifying Numeric Values in a Column

One of the easiest ways to use ISNUMBER is to check for numbers in a dataset. This is especially useful when working with imported or mixed-type data.

=ISNUMBER(A1)

This checks if the value in A1 is a number.

2. Filtering Out Non-Numeric Values

If I need to extract only numeric values from a column, I can combine ISNUMBER with FILTER (available in Excel 365 or Excel 2019).

=FILTER(A1:A10, ISNUMBER(A1:A10))

This formula returns only the numeric values from A1:A10.

3. Using ISNUMBER with SEARCH for Partial Matches

A great trick is combining ISNUMBER with SEARCH to check if a cell contains a specific substring.

=ISNUMBER(SEARCH("apple", A1))

If A1 contains the word “apple” anywhere in the text, SEARCH returns a numeric position, making ISNUMBER return TRUE. Otherwise, the formula returns FALSE.

4. ISNUMBER in Conditional Formatting

I often use ISNUMBER in conditional formatting to highlight numeric values. Here’s how:

  1. Select the range (e.g., A1:A100).
  2. Go to Conditional Formatting > New Rule.
  3. Choose Use a formula to determine which cells to format.
  4. Enter =ISNUMBER(A1).
  5. Click Format, set a preferred style, and hit OK.

Now, all numeric values in the selected range will be visually highlighted.

5. Validating User Input

When creating interactive spreadsheets, it’s useful to ensure that users enter numeric values.

  1. Go to Data Validation (under the Data tab).
  2. Select Custom as the validation criteria.
  3. Enter the formula: =ISNUMBER(A1) (assuming you want to validate column A).
  4. Click OK.

Now, Excel will only allow numeric values in the specified range.

Key Takeaways

  • ISNUMBER is a straightforward way to test if a value is numeric.
  • It works well with logical, filtering, and validation functions.
  • Combining it with SEARCH can help detect text matches.
  • It’s useful in conditional formatting and data validation.

Whether I need to clean datasets, build intelligent formulas, or ensure accurate data entry, ISNUMBER remains one of my go-to Excel functions.

 

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