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What is Lattice Multiplication?

Lattice multiplication grid with diagonal lines showing how numbers are placed and added
Example of a lattice multiplication grid

Lattice multiplication is a method for multiplying numbers using a grid. This method breaks down the multiplication process into smaller, easier steps. It's especially helpful when multiplying larger numbers because it organizes the work in a clear, structured way.

The lattice method uses a grid with diagonal lines. Each digit of the numbers being multiplied has its own cell in the grid. This method helps keep track of place values (ones, tens, hundreds) and makes it less likely to make mistakes.

Lattice multiplication has been used for hundreds of years and was popular in medieval times. It's still useful today for visual learners who benefit from seeing the multiplication process step by step.

How to Do Lattice Multiplication

Step-by-step illustration of lattice multiplication showing grid setup, multiplication, and addition phases
Step-by-step lattice multiplication process

Let's learn how to do lattice multiplication step by step. We'll use the example of multiplying 23 × 45.

Step 1: Draw the Lattice Grid

Draw a grid with rows and columns based on the number of digits in your numbers. For 23 × 45, both numbers have 2 digits, so you need a 2×2 grid. Draw diagonal lines through each cell from top-right to bottom-left.

Step 2: Write the Numbers

Write one number across the top of the grid (one digit per column) and the other number down the right side (one digit per row). For 23 × 45, you would write 2 and 3 across the top, and 4 and 5 down the right side.

Step 3: Multiply and Fill the Cells

Multiply the digit at the top of each column by the digit at the right of each row. Write the product in the corresponding cell, with the tens digit in the top left of the cell and the ones digit in the bottom right.

For example: 2 × 4 = 08 (write 0 in top left, 8 in bottom right)

Step 4: Add Along the Diagonals

Starting from the bottom right corner, add the numbers along each diagonal. If a sum is 10 or more, carry over to the next diagonal.

Step 5: Read the Answer

The final product is read from the top left to the bottom right. In our example, 23 × 45 = 1,035.

Lattice Multiplication Examples

Several completed lattice multiplication examples showing different problems and solutions
Various lattice multiplication examples

Let's look at some examples of lattice multiplication to better understand how it works:

Example 1: 12 × 34

1. Draw a 2×2 grid
2. Write 1 and 2 across the top, 3 and 4 down the right side
3. Multiply: 1×3 = 03, 1×4 = 04, 2×3 = 06, 2×4 = 08
4. Add diagonals: right diagonal: 8, next: 0+0+6=6, next: 0+0+0=0, left: 0
5. Read answer: 408

Example 2: 56 × 78

1. Draw a 2×2 grid
2. Write 5 and 6 across the top, 7 and 8 down the right side
3. Multiply: 5×7 = 35, 5×8 = 40, 6×7 = 42, 6×8 = 48
4. Add diagonals: right: 8, next: 4+4+0=8 (carry 0), next: 3+4+2+0=9, left: 4
5. Read answer: 4,368

Example 3: 123 × 45 (3-digit × 2-digit)

1. Draw a 3×2 grid
2. Write 1, 2, 3 across the top, 4 and 5 down the right side
3. Multiply each pair of digits
4. Add along the diagonals
5. Read answer: 5,535

Lattice Multiplication Quiz

Test your understanding of lattice multiplication with this 5-question quiz. Choose the correct answer for each question.

1. What is the first step in lattice multiplication?
2. How do you write the product of 7 × 8 in a lattice cell?
3. What is the correct lattice grid size for multiplying a 3-digit number by a 2-digit number?
4. How do you find the final answer in lattice multiplication?
5. Which number would you write along the top of the lattice grid for 47 × 23?

Frequently Asked Questions

Here are answers to common questions about lattice multiplication:

Math Trivia

Discover interesting facts about multiplication and mathematics:

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