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 Depdendent Variable

 Number of equations to solve: 23456789
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 Dependent Variable

 Number of inequalities to solve: 23456789
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# 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.