Multiply 2 × π × radius to get circumference.
This question focuses on calculating circumference, a key circle property. Higher-difficulty requires precision with units, correct π use, and understanding linear vs square measurements. Students should visualise walking around the circle and connecting circumference to diameter and radius. Practising these calculations develops geometric reasoning, prepares students for real-world applications like construction or design, and ensures understanding of the relationship between circumference, diameter, and radius.