Series between length units: 1 m = 10 decimeter, 1 m = 100 cm, 1 m = 1000 mm, 1 decimeter =/kloc.

Propulsion rate between units of area: 1 m2 = 100 square decimeter, 1 hectare = 1000 square meter, 1 square decimeter = 100 square centimeter, 1 square kilometer =

The forward speed between unit of volume: 1 m3 = 1000 cubic decimeter, 1 cubic decimeter = 1000 cubic centimeter, 1 cubic centimeter = 1000 cubic millimeter.

Volume: 1 l = 1 000ml = 1 decimeter cubic,1ml = 1 cm cubic.

The ratio between mass units: 1 ton = 1000 kg, 1 kg = 1000 g.

Progress between time units: average year =365 days leap year =366 days.

General year: A year divisible by 4 is a normal year.

Whole Hundred Years: The year divisible by 400 is leap year 1 hour =60 minutes, and one minute =60 seconds.