What is Long Multiplication?
Long multiplication is a method used to multiply larger numbers that you can't easily multiply in your head. It's like stacking the numbers and multiplying them one step at a time.
Step-by-Step Guide
Example: Multiply 23 by 45
Step 1: Write the Numbers
- Write the larger number on top and the smaller number right below it, aligning the digits by place value.
23
× 45
_____
Step 2: Multiply by the Ones Digit
- Start with the ones digit of the bottom number (5 in this case).
- Multiply 5 by each digit of the top number, starting from the right.
23
× 45
_____
115 (5 × 23 = 115)
Step 3: Multiply by the Tens Digit
- Next, multiply by the tens digit of the bottom number (4, which is actually 40).
- Write a zero in the ones place of the new line (because you're really multiplying by 40).
23
× 45
_____
115 (5 × 23 = 115)
+920 (40 × 23 = 920, written as 4 × 23 with a zero added)
Step 4: Add the Results
- Add the two products together to get the final answer.
115
+920
_____
1035
So, 23×45=1035.
Visual Aids
Using Grid Method (Area Model)
- Draw a Grid: Divide the numbers into tens and ones.
- 23 is 20 and 3.
- 45 is 40 and 5.
- Multiply Each Part:
- Multiply each part separately.
- 20×40=800
- 20×5=100
- 3×40=120
- 3×5=15
- Add Them Up:
- Add all the partial products.
|
x |
20 |
3 |
|
40 |
800 |
120 |
|
5 |
100 |
15 |
800
+100
+120
+ 15
____
1035
Practice Tips
- Break it Down: Take it step by step, and practice each part separately.
- Use Graph Paper: It helps keep numbers aligned correctly.
- Check Your Work: After adding, double-check by doing the multiplication again or using a calculator to see if you get the same result.
Summary
- Long Multiplication: A step-by-step way to multiply larger numbers.
- Steps:
- Write the numbers.
- Multiply by the ones digit.
- Multiply by the tens digit.
- Add the results.
- Practice and Visuals: Use grids and break the problem into smaller parts to understand better.
By following these steps and practicing, children can become confident in using long multiplication to solve larger multiplication problems.