Stretch out the metric tape measure and notice the markings on it. You will see centimeters labeled with large numbers. Between each centimeter, you will see lines indicating millimeters. Because there are 10 millimeters in each centimeter, the tape measure will have nine smaller lines between each larger centimeter line, indicating the millimeters.
Place the tape measure along an object to practice measuring. For example, if you wish to measure the width of a book, place the end of the tape measure at the left edge of the book and stretch it across to the right edge of the book.
Note the measurement on the tape measure. Using the same example, if the width of the book measures 16 centimeters and 6 millimeters, the edge of the book will come to just slightly more than the halfway point between 16 and 17 centimeters on the tape measure. Count the millimeters and you will arrive at 6 millimeters.
State the measurement in centimeters and millimeters by using decimals. Using the same example, state that the book measures 16.6 centimeters (16 centimeters, 6 millimeters).