stupid math problem

Here's this stupid logic deal. I need to find the formula, but it's probably something stupid that will take forever to find. Here's the codes, the actual word problem doesn't mean jack shit.

Column A          Column B
--------          --------
623               487
509               501
1407              9623
?                 365

Two internets to anyone who can solve this.

ah, I guess so. must've copied it wrong. thanks.