# ISNUMBER
The **ISNUMBER** function returns TRUE if the specified cell value is a valid numeric value. It returns FALSE if the value is not a number. It is commonly used with IF and other conditional functions to validate numeric inputs before performing calculations.
### Syntax
```javascript
ISNUMBER(value)
```
### Arguments
value - The value to evaluate. Required.
### **Return value**
Either TRUE or FALSE.
### **Example**
IF(ISNUMBER([2027 Plan]),[2027 Plan]*1.05,"Not a number")
In this example, the **ISNUMBER** formula checks whether the *2027 Plan* contains a numeric value and returns TRUE or FALSE accordingly. If TRUE, the IF function calculates a 5% increase in the plan value. If FALSE, it returns "Not a number".
