1, the numbers are aligned and multiplied from the unit.

2. First multiply the multiplicand by the multiplier digits, and the last digit of the number is aligned with the multiplier digits.

3. Multiply the multiplicand by the number in the tenth place of the multiplier, and the last place of the number is aligned with the tenth place of the multiplier.

4. Then add up the products multiplied twice.

Vertical calculation of multiplying one digit by multiple digits;

(1) The same number is aligned.

(2) Multiply this number by the number on each bit of the multi-digit number, starting from the single digit number, that is, from right to left.

(3) When you multiply the product by which number, write the product under the corresponding number.

(4) If you want to carry, which bit's product is more than ten bits, move forward several times, and then continue to multiply down.

Multiply with 0 at the end of an integer: you can multiply the number before 0 first, then see how many zeros are at the end of each factor, and add a few zeros at the end of the multiplied number.