## Syntax
```mermaid
%%{init: {
'theme': 'base',
'flowchart': { 'padding': '7', 'nodeSpacing': '20', 'rankSpacing': '20' },
'themeVariables': {
'fontSize': '11px',
'fontFamily': 'Arial'
}
}}%%
flowchart LR
Start((START)) --> IS_NUMBER[IS_NUMBER]:::quoted
IS_NUMBER --> End((END))
```
## Purpose
The `IS_NUMBER` SQL function determines whether a value is a valid number according to the specified format. When true, the value can be converted by `to_number`.
Parameters:
- Input: value to convert.
- Format: format mask. Optional; defaults to local style. The list of format masks is available in [[Format Masks]].
Returns: true when the value can be converted to a number, false otherwise.