How to Have different invoice numbers for CASH

HI, team
We have 2 types of customers, walkin and companies.

Walkin are cash customers.
Companies are Credit customers.

Invoicing module is fine with companies but we want the problem is the invoice numbers are running number for both customers.

How can we have separate numbers for CASH walkin customers?
Any Idea.
Thanks.

Hi,
How are the walkin customers or credit customers separated as in for example in customer order when you select the customer which one is walkin and which one is credit?

We have create 1 customer named CASH, thats what we use for walkin customer as we dont need details of walkin customer, but we do need stock deduction and payment record.

Maybe follow instructions at the invoice mask:

See that instruction ccc or cc000 (client code)

This masking is for entire Invoice module.
I am already using this mask for our customer.
I am seeking is alternative invoice number for CASH sales.

do you have resolve? i need this solution also!