A pencil is 18 centimeters long. How long is the pencil in millimeters?

To convert centimeters to millimeters, it is essential to know the relationship between the two units of measurement. One centimeter is equal to 10 millimeters. Therefore, to convert centimeters to millimeters, you multiply the number of centimeters by 10.

In this case, the pencil is 18 centimeters long. To find its length in millimeters, you would perform the following calculation:

18 cm × 10 = 180 mm.

This calculation shows that the pencil is 180 millimeters long, making this the correct answer. Converting units accurately is fundamental in mathematics, especially when precise measurements are crucial. Knowing how to properly execute such conversions ensures clarity and correctness in problem-solving scenarios.