Math worksheet for calculating the circumference of circles using diameter and radius.

I'll solve each problem step by step, calculating the circumference for all 10 circles.

Key formulas:
- Circumference = diameter × π (or d × π)
- Circumference = 2 × radius × π (or 2r × π)
- Using π ≈ 3.14

Let me work through each problem:

Problem 1: Diameter = 18 cm
Circumference = 18 × 3.14 = 56.52 cm

Problem 2: Diameter = 24 mm
Circumference = 24 × 3.14 = 75.36 mm

Problem 3: Diameter = 16 ft
Circumference = 16 × 3.14 = 50.24 ft

Problem 4: Diameter = 84 miles
Circumference = 84 × 3.14 = 263.76 miles

Problem 5: Diameter = 123 m
Circumference = 123 × 3.14 = 386.22 m

Problem 6: Radius = 4 cm
Circumference = 2 × 4 × 3.14 = 8 × 3.14 = 25.12 cm

Problem 7: Radius = 36 mm
Circumference = 2 × 36 × 3.14 = 72 × 3.14 = 226.08 mm

Problem 8: Radius = 21 ft
Circumference = 2 × 21 × 3.14 = 42 × 3.14 = 131.88 ft

Problem 9: Radius = 56 miles
Circumference = 2 × 56 × 3.14 = 112 × 3.14 = 351.68 miles

Problem 10: Radius = 90 m
Circumference = 2 × 90 × 3.14 = 180 × 3.14 = 565.2 m

Final Answer:
1. 56.52 cm
2. 75.36 mm
3. 50.24 ft
4. 263.76 miles
5. 386.22 m
6. 25.12 cm
7. 226.08 mm
8. 131.88 ft
9. 351.68 miles
10. 565.2 m