ISNUMBER() – Checks if a value is a number and returns a corresponding value

ISNUMBER(value, trueValue, falseValue)

• value: The value or cell reference to check (e.g., T1A1).
• trueValue: The value to return if the value argument is a number.
• falseValue: The value to return if the value argument is not a number.

ISNUMBER(T1A1, "Yes", "No")

This example checks if the content of cell T1A1 is a number.

• If T1A1 contains the number 123, the function returns "Yes".
• If T1A1 contains the text "text", the function returns "No".
• If T1A1 contains 456, it returns "Yes".
• If T1A1 is empty, it typically would return the falseValue (e.g., "No"), as an empty cell is not a number.

• Type checking: Specifically verifies if the data is numeric.
• Built-in branching: Directly returns one of two specified values based on the outcome, similar to an IF statement focused on number validation.

• Validating data entry to ensure users have input numbers where required: ISNUMBER(T1A1, T1A1 * 2, "Invalid input: Please enter a number").
• Preventing errors in calculations by checking if a cell contains a number before using it in an arithmetic operation.
• Categorizing data based on whether it's numeric or text.

• Text values not in quotes: The trueValue and falseValue, if text, must be enclosed in double quotes.
• Expecting a TRUE/FALSE boolean return: MathGrid returns one of the two arguments (trueValue or falseValue) provided by the user.