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.

4, the minute hand goes around and the hour hand goes by a big grid, which is 1 hour. The second hand turns, and the minute hand occupies a small space. 1 minute.

5. Time is the relationship between two numbers. How much is a number, and another water can be said that one number is several times that of another. Find how many times one number is another, that is, how many other numbers are there in a number. It is calculated by dividing one number by another.