Math Playground
Activities

Binary Fingers

Count to 31 on one hand — meet binary in your bones.

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.

Try this
13
in binary (thumb=1, index=2, middle=4, ring=8, pinky=16) = 01101
Your turn

Which fingers are up for the number 22?

Add the second hand and you reach 0–1023 — that hand's fingers are worth 32, 64, 128, 256, 512. Computers count exactly this way.

Recap
  • Each finger is a bit: down = 0, up = 1.
  • Values double along the hand: 1, 2, 4, 8, 16.
  • Add the raised fingers to read the number.
  • One hand → 0–31; two hands → 0–1023.

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.