> For the complete documentation index, see [llms.txt](https://appmaster.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://appmaster.gitbook.io/docs/business-logic/block/group-validators/untitled-8.md).

# Validate Bank Card Number (Luhn)

Checks the entered data for compliance with the format of the bank card number.

The analysis uses the [Luhn algorithm](https://en.wikipedia.org/wiki/Luhn_algorithm). 

### Stream connectors 

* \[Input] In - starts block execution. 
* \[Output] Out - is activated when the block has finished executing. 

### Data connectors 

* \[Input] card\_number (string) - the value to check for compliance with the format. \[
* Output] is\_valid (boolean) - if the value matches the format, it returns the value True, otherwise - False.