1, decimal multiplication by integer has the same meaning as integer multiplication, and it is a simple operation to find the sum of several identical addends.

2. If one factor remains unchanged, another factor expands (shrinks) by n times, and the product also expands (shrinks) by n times; One factor is enlarged by n times and the other factor is reduced by n times, and the product remains the same.

3, a number (except 0) multiplied by a number greater than 1, the product is greater than the original number; A number (except 0) is multiplied by a number less than 1, and the product is less than the original number.

4. Divide the decimal by the integer, and then divide it by the integer. The decimal point of quotient should be aligned with the decimal point of dividend. The integer part is not divided enough, quotient 0, decimal point. If there is a remainder, add 0 and divide it.

5. In practical application, the quotient obtained by fractional division can also be calculated by "rounding", and a certain number of decimal places can be reserved as needed.