1. Commonly used length units are: kilometer (km), meter (m), decimeter (dm), centimeter (cm) and millimeter (mm). Except that the propulsion rate between kilometers and meters is 1000, the propulsion rate between other two adjacent length units is 10.
2. Area units: square kilometers, hectares, square meters, square decimeters, square centimeters and square millimeters. Examples in life are close to 1 cm2, 1 cm2, 1 m2. For example, 1 cm2 can represent the key surface size of fingernails and keyboards, 1 cm2 can represent the size of switch boxes and adult palms, and 1 m2 can represent the size of a floor tile in the classroom.
3. Common mass units: ton (t), kilogram (kg) and gram (g). Mass: refers to the weight of an object. Common conversions: 1t = 1000kg, 1kg = 1000g, 1kg = 1kg.
Correct use of units
In mathematics, the unit is a standard used to measure or express quantity. It can be a standard quantity to compare the sizes of other similar quantities. Units are usually used to describe physical quantities such as length, mass, time, temperature and speed.
Units can be divided into basic units and derivative units. Basic units are independent and inseparable units, such as meters, kilograms, seconds, etc. Derived units are units based on the combination of basic units, such as square meters, kilograms/cubic meters, etc.
In mathematics, the use of units can help us to quantify and measure various physical and mathematical concepts, so as to accurately calculate, compare and analyze them. The selection and use of units should conform to the international system of units (SI system) commonly used in the world or the system of units in other specific fields.