Be sure to check it when you are finished. You can use different inspection methods to check, and the correct rate will definitely be lower if you only calculate it once. Usually, when doing vertical multiplication, we should pay attention to the alignment of the unit of product with the unit of multiplicand and multiplier.
When calculating multiplication, you must remember that you must add the nearest number to the front. You must remember clearly that there are hundreds when there are many people and thousands when there are many people. This is the most important point.
First, use a single digit, and don't look at the zeros at the ends of the two multipliers. Then, multiply the two digits by one digit to calculate the number. Then, look at how many zeros are at the end of the two multipliers, and add a few zeros at the end of the numbers.
Multiplication needs to overcome some technical obstacles, first of all, it needs to be nested in a loop, and then it can be accumulated bit by bit through an array, and finally the carry work can be completed uniformly.