If you use the "Apply a regular expression" action with the Replace operation, you can use the following pattern and replacement text to get a text variable with commas separators.

Pattern: ([0-9]{1,3})(?=([0-9]{3})+(?![0-9]))

Replacement text: $1,

The above configuration results in this value for the test variable: 123,456,789

Thank you so much!! My issue was resolved!!

Best Regards,
Smita