Chinese hand signing system for digits

Jesse taught me a Chinese drinking game where you roll dice onto the table and do some wagers on what the dice are showing under the cups. To play this game, he taught me the sign language for the numbers 1 through 10.

I thought this signing system was just for this game, but a girl that was selling me some crackers on the train just now used those same hand motions to tell me how much it was when I didn't understand what she was saying.

I was very surprised. I almost felt like doing the same thing back to her just to show her I'm down with that!