The counting principle, step by step
Four shirts and three pairs of shorts make twelve outfits, not seven.
The question
3 frames, 2 wheels and 4 colors. How many different bikes can you make?
3 frames, 2 wheels and 4 colors. How many different bikes can you make?
324
3×2=6
6×4=24
- Each of the 3 frames can go with every one of the 2 wheels, so the choices multiply — they do not add.
- First two stages: 3 × 2 = 6.
- Then the 4 colors: 6 × 4 = 24.
How it works.
- 01
Each of the 3 frames can go with every one of the 2 wheels, so the choices multiply — they do not add.
- 02
First two stages: 3 × 2 = 6.
- 03
Then the 4 colors: 6 × 4 = 24.