The square area used in the shortcut method for a circle with a diameter of 20 feet is:

• A. 200 sq ft
• B. 600 sq ft
• C. 800 sq ft
• D. 400 sq ft

Answer: (D)

The shortcut method uses a square whose side equals the circle’s diameter. Its area is D squared. With a diameter of 20 feet, the square area is 20 × 20 = 400 square feet. If you wanted the circle’s actual area, it would be about π/4 of that square, which is roughly 0.785 × 400 ≈ 314 square feet.