Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

I received $1000 and was asked to send it back. How was this scam meant to work?
I would have asked for the intended recipient's account number and pursue sending the money there. If it's the same as yours (except for one digit) that would be a good sign. But even here, the crook could send money to dozens of different accounts, all off by one digit, just to make it look authentic. I'm going with scam just to be safe. As for the checksum, it's used on paper checks (next to the last digit) but not necessarily the actual account. Credit card accounts use an algorithm, but online tools create as many legitimate character strings as you want. I used to work at a credit union, and when the time was just right, I opened account number 860000 (actual account number except for the second digit). All their account numbers were sequential, so the oldest account number was 000001. Sadly, many important systems are set up to meet the simple needs of the masses, and are easy to beat if you really want to. Check out If you dare hackers to hack you, they'll hack you good.