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How to Learn Long Multiplication?

Published in Math Education 3 mins read

Learning long multiplication involves a step-by-step process that, with practice, becomes easier. Here's a breakdown of how to approach it, incorporating the key takeaway from the reference:

Understanding the Basics

Long multiplication is used to multiply larger numbers that cannot be easily computed in your head. It essentially breaks down the multiplication process into smaller, more manageable steps.

Steps for Long Multiplication

  1. Set Up the Problem:

    • Write the two numbers you want to multiply, one above the other.
    • Draw a line underneath the bottom number.
    2 3
    x 1 2
    --- ---
  2. Multiply by the Ones Place:

    • Multiply the ones digit of the bottom number by each digit of the top number, working from right to left.
    • Write the result below the line, aligning the ones place with the ones place of the numbers being multiplied.
    2 3
    x 1 2
    --- ---
    4 6
  3. Multiply by the Tens Place:

    • Move to the tens digit of the bottom number. Before multiplying, write a zero as a placeholder under the ones place of the previous result. This is done because we are now multiplying by the tens digit.
    • Multiply the tens digit by each digit of the top number from right to left.
    • Write the result on the second line, properly aligned.
    2 3
    x 1 2
    --- ---
    4 6
    2 3 0
  4. Add the Partial Products:

    • Add the numbers from all of your multiplication steps vertically. This is called adding the partial products.
    • Start from the rightmost column and carry over any digits that exceed 9 to the next column.
    2 3
    x 1 2
    --- ---
    4 6
    2 3 0
    --- ---
    2 7 6
  5. The Final Answer:

    • The result of the addition is your final answer to the long multiplication problem.

Example

Let's multiply 23 by 12, as seen in the table above:

  • Step 1: 2 * 3 = 6
  • Step 2: 2 * 2 = 4. Result: 46
  • Step 3: 1 * 3 = 3. Since the 1 is in the tens place, add a 0 first: 30
  • Step 4: 1 * 2 = 2. Result: 230
  • Step 5: 46 + 230 = 276

The answer to 23 x 12 is 276.

Key Points and Practice

  • Practice is Crucial: The provided reference states that "practicing is the best way to get used to long multiplication." Consistent practice reinforces the steps and builds confidence.
  • Alignment: Maintaining correct alignment of numbers is key to getting the right answer.
  • Start Simple: Begin with smaller numbers and gradually increase the size as your skills improve.
  • Break it Down: Remember, long multiplication breaks complex multiplication into easier, manageable steps.
  • Review and Correct: Check your work to correct errors and reinforce proper technique.

By following these steps and practicing regularly, you will effectively learn long multiplication.