How many square millimeters are in one square meter?

• A. 1,000 square mm
• B. 1,000,000 square mm
• C. 10,000 square mm
• D. 100 square mm

Answer: (B)

Think about how area scales with the metric system. Convert the length to millimeters, then square. One meter equals 1,000 millimeters, so a square meter has side length 1,000 mm. The area is 1,000 mm × 1,000 mm = 1,000,000 square millimeters. So there are 1,000,000 mm^2 in one m^2. The other numbers come from using the linear conversion without squaring, which isn’t correct for area.