Analysis: Starting from the right, multiply the first factor by the number on each bit of the second factor, and the end of the number will be aligned with which bit of the second factor is on which bit of the factor. Then add up the numbers multiplied by several times.

First calculate 25 times 4 equals 100, then calculate 25 times 20 equals 500, and then add 100 and 500 to get 600.

Extended data:

First, the vertical calculation of multiple digits multiplied by one digit

1, aligned with the same number.

2. Multiply this number by the number on each of multiple numbers, starting with a single number, that is, from right to left.

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

4. If you want to carry, the product of which bit is more than dozens, just move forward a few times and then continue to multiply down.

2. How many digits is the multiplication of two digits?

1, write the factors with more digits, and write the factors with fewer digits.

2. The following factors should be aligned with the numbers of the factors written on them.

3. Multiply the single digits of the second factor (the factor written below) with the single digits of the number written above, write the last digit of the product obtained by multiplication on the single digits, then multiply it with the number in the tenth place and write it on the tenth place.

4. If the product of one bit is more than tens, move forward several times and then continue to multiply.

5. Multiply each digit of the factor written below with each digit of the factor written above, and write the last digit of the multiplied product on the corresponding ten digits.

6. Then add up the numbers multiplied each time.