Algorithm of decimal multiplication:
1. First, the product is calculated according to the rule of integer multiplication;
2. Then look at how many decimal places there are between the multiplicand and the multiplier. Count from the right side of the product and point to the decimal point;
3. If zero appears at the end of the decimal, the zero at the end of the decimal shall be crossed out according to the basic nature of the decimal.
The vertical form means that each transition number is multiplied by 2 after the previous transition number changes. If carry is required, advance 1 to the front, and then advance the single digit to ten digits, and so on, while the single digit is supplemented with new arithmetic digits.