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The Rule for 12: Double and Add Neighbor

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The Trachtenberg rule for 12 builds beautifully on the method for 11. It uses the same "neighbor" concept but adds a simple "doubling" step, making it another fast and efficient tool for your mental math toolbox.

The Rule: "Double the Digit and Add its Neighbor"

To multiply any number by 12, work from right to left. For each digit, you **double it** and then **add its neighbor** to the right.

Example: Multiply 48 by 12

Add a leading zero: 048.

  1. Digit 8: Double 8 (16) + neighbor (0) = 1616. Write 6, carry 1.
  2. Digit 4: Double 4 (8) + neighbor (8) + carry (1) = 1717. Write 7, carry 1.
  3. Digit 0: Double 0 (0) + neighbor (4) + carry (1) = 55. Write 5.

The final answer is 576.

🔢Multiplication by 12 Lab

Enter any number to see the step-by-step "Double and Add Neighbor" method.

🧠Quick-Fire Quiz!