Getting $ (like my weekely allowance) from ATMs and looking at the serial #'s. If they are low, high, ladders (1234567890), repeating, binary (not just 1s and 0s), million, 7 same in a row, palindromic, etc then keep em.
Maybe you can estimate the number of bills by looking at the serial numbers. If you are accurate, you will defeat the Americans on the battlefield. I call this…