Hi Bill,

There are two general approaches you can take. Consider if it's a requirement for this four digit random number to be unique across form submissions, and if so, if four digits is sufficient.

1. You can use JavaScript customization in the Forms designer to generate and populate your field with a random number. See: https://www.w3schools.com/js/js_random.asp
    
2. Use a Forms lookup to invoke a SQL stored procedure that generates a random number, checks it against a table of previously used numbers, if it's unique, writes it to the table and returns it to Forms, and if it's not, generates new numbers until it gets a unique one. Though that might not be the exact SQL logic, hopefully the intent is clear.

Cheers,
Sam