Math worksheet for calculating the area of circles with given radii.

To find the area of a circle, we use the formula:
Area = π × r²
We are told to use π = 3.14.

Let’s solve each problem one by one. Remember: if you’re given the diameter (a line across the circle through the center), divide it by 2 to get the radius. If you’re given the radius (from center to edge), use it directly.

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Problem 1: Radius = 18 yd
Area = 3.14 × (18)² = 3.14 × 324 = 1017.36 yd²

Problem 2: Diameter = 10 cm → Radius = 5 cm
Area = 3.14 × (5)² = 3.14 × 25 = 78.5 cm²

Problem 3: Radius = 6 m
Area = 3.14 × (6)² = 3.14 × 36 = 113.04 m²

Problem 4: Diameter = 40 ft → Radius = 20 ft
Area = 3.14 × (20)² = 3.14 × 400 = 1256 ft²

Problem 5: Diameter = 16 yd → Radius = 8 yd
Area = 3.14 × (8)² = 3.14 × 64 = 200.96 yd²

Problem 6: Radius = 54 m
Area = 3.14 × (54)² = 3.14 × 2916 = 9156.24 m²

Problem 7: Radius = 8.8 m
Area = 3.14 × (8.8)² = 3.14 × 77.44 = 243.1616 m² → Round to two decimals? Let’s keep as is unless specified. But since others are rounded to 2 decimals, we’ll do same: 243.16 m²

Wait — let me recalculate that:
8.8 × 8.8 = 77.44
3.14 × 77.44:
First, 3 × 77.44 = 232.32
Then 0.14 × 77.44 = 10.8416
Total = 232.32 + 10.8416 = 243.1616 → So yes, 243.16 m² when rounded to two decimal places.

Problem 8: Radius = 30 mm
Area = 3.14 × (30)² = 3.14 × 900 = 2826 mm²

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Double-checking all calculations:

1. 18²=324; 324×3.14 → 300×3.14=942, 24×3.14=75.36 → total 1017.36 ✔
2. 5²=25; 25×3.14=78.5 ✔
3. 6²=36; 36×3.14=113.04 ✔
4. 20²=400; 400×3.14=1256 ✔
5. 8²=64; 64×3.14=200.96 ✔
6. 54²=2916; 2916×3.14 → 2900×3.14=9106, 16×3.14=50.24 → total 9156.24 ✔
7. 8.8²=77.44; 77.44×3.14=243.1616 ≈ 243.16 ✔
8. 30²=900; 900×3.14=2826 ✔

All correct.

Final Answer:
1. 1017.36 yd²
2. 78.5 cm²
3. 113.04 m²
4. 1256 ft²
5. 200.96 yd²
6. 9156.24 m²
7. 243.16 m²
8. 2826 mm²