Number 25

The number 25 sign looks like the ASL number '5' hand, only it starts out facing outward. Then bend your middle finger forward twice, as if to show the demarcation of a compound sign: the letter L (which stands for the number '2' in '20' onwards), then the number 5 facing outward. The wiggling middle finger reveals the '2' of '20', but when the finger is upright, you see the number '5'.