If the number is multiplied by 12 to 19 then following method is to be followed.

Let’s understand this method by taking an example.

345 × 12

Step 1:

Write 345 as 0345.

Step 2:

Multiply each and every digit with 2 and add it to its right neighbor. This process is started from right. Multiply 5 with 2 and add it to its right neighbor. 5 has no right neighbor so add the multiplication to 0. This gives 10 as a result. So 0 is written down and 1 is carried forward.

Step 3:

Multiply 4 with 2 and add it to 5. Carry 1 is added to the result. This gives 14 as a result.

4 is written down and 1 is carry forwarded.

Step 4:

Multiply 3 with 2 and add it to 4. Carry 1 is added to the result. This gives 11 as a result.

1 is written down and 1 is carry forwarded.

Step 5:

Multiply 0 with 2 and add it to 3. Carry 1 is added to the result. This gives 4 as a result.

You can take this procedure as standard procedure.

Now, if the number is multiplied by 13 then multiply each and every digit with 3 instead of 2. And rest of the procedure is same.

If the number is multiplied by 14 then multiply each and every digit with 4 instead of 2. And rest of the procedure is same.

If the number is multiplied by 15 then multiply each and every digit with 5 instead of 2. And rest of the procedure is same.

If the number is multiplied by 16 then multiply each and every digit with 6 instead of 2. And rest of the procedure is same.

If the number is multiplied by 17 then multiply each and every digit with 7 instead of 2. And rest of the procedure is same.

If the number is multiplied by 18 then multiply each and every digit with 8 instead of 2. And rest of the procedure is same.

If the number is multiplied by 19 then multiply each and every digit with 9 instead of 2. And rest of the procedure is same.