Decimal times decimal

Knowledge point one:

Relationship between factor and product decimal places: factor * * has several decimal places, and product also has several decimal places.

Knowledge point 2:

General calculation method of decimal multiplication:

First calculate the product by integer multiplication, and then multiply the product by the decimal point of the product point. There are not enough decimal places in the product. Add 0 in front and 0 after the decimal point.

Knowledge point 3:

Calculation method of decimal multiplication:

Multiply the positions of factors by exchange.