How can I assign a unique number response to each submission?

I want both the respondent and recipient to get a unique number from each submission.

I have created a credit form and I want to be able to reference a specific number for accounting purposes.

You can assign unique IDs on your submissions by following this guide: https://www.jotform.com/help/79-How-to-Add-Custom-Unique-IDs-to-your-Form-Submissions. 

You'll need to use the Unique ID widget, it's alright to setup multiple ones and add them separately on your form alerts (autoresponder email and notification email).

Let us know if that works.