Which unit would be best for measuring the distance between two towns?

• A. Centimeters
• B. Meters
• C. Kilometers
• D. Millimeters

Answer: (C)

Distances between towns are long, so you want a unit that keeps the numbers reasonable. Centimeters and millimeters are for very small objects, so using them would give you huge, awkward numbers like millions of millimeters. Meters can work for moderate distances, but road distances between towns are usually much larger than a few hundred meters. Kilometers are the standard unit for these long distances because they compress big lengths into manageable numbers; for example, 15,000 meters is 15 kilometers, which is much easier to read and compare. So using kilometers makes the distance between towns clear and practical.