Find the zero mark at the start of the tape
Read the numbered marks labeled in centimeters
Each long numbered line usually represents 1 cm
Count the smaller lines between the numbered marks
Each small line usually represents 1 mm
10 mm equals 1 cm
Read the number at the last full centimeter mark before the measurement ends
Add the number of millimeter marks after that centimeter
Example: 7 full cm plus 4 small marks equals 7.4 cm
Use the side of the tape labeled cm, not inches
Keep the tape straight for an accurate reading