Each finger is a binary digit: down = 0, up = 1. Five fingers, five binary digits — you can count from 0 to 31 on one hand.
The values
- Thumb = 1
- Index = 2
- Middle = 4
- Ring = 8
- Pinky = 16
Try it
Show 13 on your hand
13 = 8 + 4 + 1. Ring up, middle up, thumb up. Index and pinky down.
Two hands gives you 0–1023. Computers count this way; you can too.