2. Fractions with denominators of 10, 100, 1000 can be expressed in decimals, where the decimals representing one tenth are one decimal place, the decimals representing percentage are two decimal places, and the decimals representing one thousandth are three decimal places. ...
3. Composition of decimals: The decimal point is the boundary, and decimals consist of integer parts and decimal parts.
4. Decimal digits, calculation unit and rate:
(1) The counting units of decimals are one tenth, one hundredth and one thousandth ... Write 0. 1, 0.0 1, 0.00 1 ... Just like integers, the progressive rate between every two adjacent counting units of decimals is 10.
② The maximum unit of calculation for the decimal part is one tenth, and there is no minimum unit of calculation for the decimal part.
③ The number of decimal places is infinite.
In a decimal, there are several decimal places after the decimal point, that is, several decimal places. The zero at the end of the decimal part is also counted.
5. Decimal reading and writing: When reading decimals, from left to right, read the integer part by integer method (the integer part is read as "zero") and the decimal part is read as "dot". The decimal part reads the number on each digit in turn, even if it is a continuous zero.
Decimals are also written from left to right. The integer part is written as an integer (the integer part is written as "0"), the decimal point is in the lower right corner of the unit, and the decimal part writes the numbers on each digit in turn.
6. Understand the difference between 0. 1 and 0. 10: Difference: 0. 1 means 1, and 0. 10 means 10, with different meanings. Contact: 0. 1=0. 10 Two numbers are equal in size. Using the basic properties of decimals, we can rewrite or simplify decimals without changing the size of numbers.
7. Decimals whose integer part is 0 are called pure decimals; Decimals whose integer part is not 0 are called decimals.