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This part of the extended materials mainly examines the knowledge points of infinite decimals:

After being converted into decimals by calculation, the decimal part is endless and can't be divisible. Decimal counting method: 10 one is ten, 10 ten is hundred ... 10 ten billion is one hundred billion, and the advancing rate between every two adjacent counting units is ten. This counting method is called decimal counting method.

When measuring an object, you often get a number that is not an integer. So the ancients invented decimals to supplement integers. Decimal is a special form of decimal.

The point in the decimal is called the decimal point, which is the dividing line between the integer part and the decimal part of a decimal. The part to the left of the decimal point is an integer part, and the part to the right of the decimal point is a decimal part. Decimals with zero integer parts are called pure decimals, and decimals with non-zero integer parts are called decimals. For example, 0.3 is a pure decimal and 3. 1 is a decimal.