In accounting, check numbers are an internal control to the company issuing them. Banks don't give a hoot what number is on a check. For example, my automatic payment to vendor xxx uses the same 'check number' every month.
Speaking of fraud, most people don't realize that credit card numbers have a structure. The first six (?) are the issuing bank id (visa starts with 4, mastercard with 5, amex and diners with 6, store cards vary). The remaining numbers are the account number - with the last number being calculated by each number coming before it (it's called 'check digit verification' and allows computer programs to immediately verify that a number is a valid credit card number - not that it's a valid account, but just that it's a valid number).
A crook can take the bank id numbers from any card and then generate totally valid credit card numbers. If you get several attempts at entering the card, you might be able to guess the correct expiration date. This is how they can get YOUR number without ever seeing your card. There are still many online payment portals that don't ask for the security code from the card.
Many years ago I had someone dumpster dive at the apartment I lived in. They found a used checkbook that I apparently hadn't torn into enough pieces. There were still deposit slips on the thing, and they deposited phony checks into my account with cash back. SIX branches let them do this. I believe two or three checked my signature card, and even though they MISSPELLED my name, they STILL let them do it!!!! Key bank. Not very bright people. When I was at the branch trying to get it all cleared up, they wanted me to sign a note saying I would appear in court on their behalf. When I asked if they were going to cover my missed wages, and they said no, I told them I wouldn't be signing until they crossed that off. They asked me to take my money and find myself another bank! Really? YOU let someone into my account and now blame me. Key bank. Keep that in mind when shopping for a new financial institution.