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Circumference (π = 3)
★★★Circumference = diameter × π, and π is about 3.14.
Ratio Galaxy · Learn first
Example
A circle has radius 9 cm. What is its circumference? (π = 3)
Answer: 54 cm
Circumference and area · Measurement
Use π to find circumference and area, first with 3, then with 3.14.
Circumference = diameter × π, and π is about 3.14.
This is step 1 of unit 5, “Circumference and area”, in Stage 7: Dividing fractions and decimals, ratio and percent, circles and volume (ages 13). A round has 10 problems; 90% or better earns three stars. Everything is free with no sign-up, and your stars and XP are saved on this device.