What is the width of a dime?

• A. 18 mm
• B. 16 mm
• C. 20 mm
• D. 22 mm

Answer: (A)

Diameter is the width across a round object, measured through the center. For a dime, this distance is about 17.91 millimeters, which is commonly rounded to 18 millimeters. So the best choice is 18 mm. The other options are farther from the dime’s actual size—16 mm would be a bit too small, while 20 mm and 22 mm are larger than the dime's true diameter. If you use inches, note that 0.705 inches equals about 17.9 mm, reinforcing the 18 mm rounding.