Printable
Binary numbers
A light switch has two settings, on and off. Line up five of them and you can name every letter of the alphabet. This page explains how.
| Place value | 16 | 8 | 4 | 2 | 1 |
|---|---|---|---|---|---|
| Binary | 0 | 1 | 0 | 1 | 1 |
How it works
- Binary uses only two digits, 0 and 1, the way a switch is only off or on.
- Each place is worth twice the one to its right: 16, 8, 4, 2 and 1.
- To read a binary number, add the place values that have a 1 under them. 01011 is 8 + 2 + 1 = 11.
- Number the letters A = 1 to Z = 26, and five places are enough for every letter: K is 11, which is 01011.
How to use it
- Write 16, 8, 4, 2, 1 across the top of a page and try small numbers first: 1, 2, 3, 4.
- Use five paper cups or five cards, face up for 1 and face down for 0, and build numbers together.
- Then try the Binary Code puzzles, which start with a full key.