If both numbers end with zeros, then multiply those digits that are not zeros, then add all zeros from both numbers to the result.

Example 1. multiply 20 by 30.

20 x 30

We see that both numbers contain zero. First we multiply the digits that are not zeros. These are the digits two and three. Two multiplied by three is six:

20 x 30 = 6

Now add all zeros from both numbers to the result, that is, to the number 6. Number 20 has one zero, number 30 also has one zero. Total two zeros. We add two zeros to number 6

20 x 30 = 600

Example 2. Multiply 40 by 300

First multiply the digits that are not zeros. These are the digits 4 and 3. Four times three is twelve:

40 x 300 = 12

Now add all zeros from both numbers to the result, that is, to the number 12. Number 40 has one zero, number 300 has two zeros. Total three zeros. We add three zeroes to number 12

40 x 300 = 12000

Example 3. Multiply 600 by 3000

First multiply the digits that are not zeros. These are the digits 6 and 3. Six multiplied by three is eighteen:

600 x 3000 = 18

Now add all zeros from both numbers to the result, that is, to the number 18. Number 600 has two zeros, number 3000 has three zeros. That makes five zeros. We add five zeroes to number 18

600 x 3000 = 1800000