1. In daily life, relatively few items can be measured in millimeters (mm), centimeters (cm) and decimeters (dm).
2. When calculating the length, you can only add or subtract the same length unit; When the units are different, they should be converted into the same units before calculation.
3. 1 m = 100 cm 1 decimeter = 100 mm; 10 decimeter = 1 m10cm = 1 decimeter10mm = 1 cm.