Unit 2: The decimal point of quotient should be aligned with the decimal point of dividend. Add 0 to the end of the decimal, and the size of the decimal remains the same. Write 0 as a placeholder unless it is not a quotient 0. Using the property of quotient invariance, fractional division can be transformed into integer division. Decimal digits are finite decimals, which are called finite decimals; The decimal places are infinite decimals, which are called infinite decimals. The decimal part of the cyclic decimal, that is, the numbers that appear repeatedly in turn, is called the cyclic segment of this cyclic decimal.
Unit 3: When you look at an object from one direction, you can see at most three sides of the object.