1, the last bit is aligned.

2. Multiply the digits of the lower multiplier with the digits of the upper multiplier, and the digits of the product are aligned with the digits of the lower multiplier.

3. Multiply the ten digits of the multiplier below by the two digits above, and the digits of the product are aligned with the ten digits of the multiplier below.

4. Add the products calculated twice.

Simple algorithm:

1, the sum of single digits is equal to 10, and the multiplication of the same ten digits: the number of ten digits plus 1 multiplied by another ten digits drops, and the multiplied two digits drop, and the number formed by these dropped digits is the even number multiplied by these two digits.

2. The sum of ten digits is equal to 10. Multiplication with the same number of digits: two digits multiplied by one digit decrease, and one digit multiplied by one digit decrease. These numbers make up an even number multiplied by these two digits.

3. Multiplication algorithm of arbitrary two-digit numbers: the number is multiplied by the single digit mantissa, and the decimal digits are recorded; Add up the figures obtained by cross multiplication of the upper and lower digits, and the mantissa of the previous decimal digit drops, and record the decimal digit, and the number composed of all the dropped digits is the final number.