## Syntax
```mermaid
%%{init: {
'theme': 'base',
'flowchart': { 'padding': '7', 'nodeSpacing': '20', 'rankSpacing': '20' },
'themeVariables': {
'fontSize': '11px',
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flowchart LR
Start((START)) --> IS_NUMBER[IS_NUMBER]:::quoted
IS_NUMBER --> End((END))
```
## Purpose
The `IS_NUMBER` SQL function evaluates to true when a value is representing a valid number. A valid number can be cast to a `number` value using [[TO_NUMBER]].
Parameters:
- Input (`ANY`): value to test whether a cast to `number` is possible.
- Format: format mask. Optional; defaults to configured number format. The list of format masks is available in [[Format Masks]].
Returns: true when the value can be cast to a number, false otherwise.
## Examples
The following example determines whether `'1234567890'` can be cast to a `number`:
```sql
select is_number('1234567890')
----------------
true
```
The following example determines whether `'A123'` can be cast to a `number`:
```sql
select is_number('A123')
----------------
false
```