Circumference of a circle
The question
cm
Circumference: circle marked 4 cm
How it works.
- 01
The 4 cm marked here goes right ACROSS the circle — it is the diameter, the whole way across, which is exactly what a circumference needs.
- 02
Circumference is π × the whole way across — that is the diameter, 4.
- 03
Then multiply by π: 4 × 3.14 = 12.56 cm. A little over three times across, as π says.