Multiplication by 12
To multiply a number by 12, follow these steps:
 Multiply the last digit by 2. Write down the last digit
of this product and carry if necessary.
 Move to the next digit to the left.
 Multiply that digit by 2 and then add that product to the
digit on its right. Finally, add the carry from the
previous steps. Write down the last digit and carry if
necessary.
 Continue to move to the left, multiply by 2, add to the
right, write and carry until you reach the end of the
number.
 At the end, you will have to multiply the leading 0 by 2
and then add to the right.
Example:
31 Ã— 12 =
Multiply 1 by 2. 1 Ã— 2 = 2. 
2 
Move to the left and to the 3. 

Multiply 3 by 2, and then add 1 (the
number on the right). 

(3 Ã— 2) + 1 = 6 + 1 = 7. 
72 
Move to the left again, but since there
is no more numbers, you use 0. 

Multiply 0 by 2, and then add 3 (the
number on the right). 

(0 Ã— 2) + 3 = 0 + 3 = 3 
372 
31 Ã— 12 = 372.
Example:
917 Ã— 12 =
Multiply 7 by 2. 7 Ã— 2 = 14. Write 4,
carry 1. 
4 
(carry 1) 
Move to the left and to the 1. 


Multiply 1 by 2, and then add 7 and add
the carry. 


(1 Ã— 2) + 7 + 1 = 10. 


Write 0, carry 1. 
04 
(carry 1) 
Move to the left and to the 9. 


Multiply 9 by 2, and then add 1 and then
add the carry. 


(9 Ã— 2) + 1 + 1 = 20 


Write 0, carry 2. 
004 
(carry 2) 
Move to the left and to the invisible 0. 


Multiply 0 by 2, add 9 and add the carry.
9 + 2 = 11. 


Since this is the last number, write the
whole number down. 
11004 

917 Ã— 12 = 11004.
