Lattice multiplication for children

Quick answer

Lattice multiplication is an old method of multiplying numbers using a grid. You can use it to multiply any two numbers together, even big ones. It helps you keep your work neat and makes it easier to avoid mistakes.

Learning outcome

By the end of this page, you will understand how to use the lattice method to multiply two numbers together, and you will be able to solve multiplication problems using a grid layout.

• You can draw a lattice grid for any two-digit multiplication.
• You can fill in the grid with the correct products of single digits.
• You can add the numbers along the diagonals to get your final answer.
• You can use this method to multiply larger numbers too.

Why this matters

Learning lattice multiplication helps you understand how multiplication works in a different way. It’s a visual method that can help you keep your work neat and avoid errors. You might even see this method in old books or history lessons! It’s also a fun way to practice your multiplication facts.

How it works

The lattice method is a way of multiplying numbers using a grid. Here’s how it works:

1. Draw a grid with the same number of rows and columns as the digits in your numbers.
2. Write the digits of the first number along the top of the grid.
3. Write the digits of the second number along the right side of the grid.
4. Fill in each box with the product of the top digit and the right digit.
5. Split each box into two triangles, and write the tens digit in the top triangle and the units digit in the bottom triangle.
6. Add the numbers along each diagonal and carry if needed.
7. Read the answer from the bottom and left side of the grid.

Examples you can see

Let’s try multiplying 23 × 14 using the lattice method.

Now, split each box into two triangles:

Fill in the top and bottom triangles:

Now, add the numbers along the diagonals:

• Bottom right diagonal: 2
• Next diagonal: 3 + 8 = 11 → write 1, carry 1
• Next diagonal: 2 + 1 + 1 = 4
• Top left diagonal: 0 + 0 = 0

Your final answer is 322.

Try it as a mini adventure

Imagine you are a medieval merchant who needs to calculate how much money you’ll make from selling 37 items at 24 pounds each. You have a big ledger and a special grid to help you multiply.

1. Draw a grid with 2 rows and 2 columns.
2. Write 3 and 7 along the top, and 2 and 4 along the right side.
3. Fill in the boxes with products.
4. Split each box into triangles and write the tens and units.
5. Add the diagonals and carry if needed.
6. Read your answer from the grid.

You discover that 37 × 24 = 888 pounds. You’re a master of the old method!

Common mistakes

• Mistake: Forgetting to split the box into two triangles. Why it happens: The grid looks confusing at first. Fix: Always split each box into two triangles and write the tens digit in the top triangle and the units in the bottom.
• Mistake: Adding the numbers in the wrong diagonal. Why it happens: Not paying attention to the direction of the diagonals. Fix: Start from the bottom right and move up to the top left, adding each diagonal carefully.
• Mistake: Forgetting to carry numbers when adding diagonals. Why it happens: Adding numbers quickly without checking. Fix: Write down any carry numbers clearly and add them to the next diagonal.

Parent and carer guide

Help your child practice lattice multiplication by:

• Using a pencil and paper to draw grids together.
• Practising with small numbers first, like 12 × 13.
• Checking that they split each box into two triangles.
• Encouraging them to double-check their addition along the diagonals.
• Using real-life examples, like calculating the total cost of items in a shop.

Remember: It’s okay if your child makes mistakes at first. The lattice method takes practice, but it’s a helpful tool for multiplying larger numbers.

Practice questions

1. Use lattice multiplication to find 24 × 35.
2. Try 17 × 28.
3. Calculate 46 × 19.
4. What is 32 × 41 using the lattice method?
5. Use the method to find 53 × 27.

Answers:

1. 840
2. 476
3. 874
4. 1312
5. 1431

FAQ

What is lattice multiplication?

Lattice multiplication is an old method of multiplying numbers using a grid. It helps you keep your work neat and makes it easier to avoid mistakes.

Who invented the lattice method?

The lattice method was used in medieval times, especially in India and the Middle East. It was later introduced to Europe.

Is lattice multiplication better than regular multiplication?

Both methods work well. Lattice multiplication can be easier for some people because it keeps everything neat and structured, especially for larger numbers.

Can I use lattice multiplication for big numbers?

Yes! You can use lattice multiplication for any size of numbers. Just make a bigger grid.

Why do we still learn lattice multiplication?

It helps you understand how multiplication works in a new way. It also shows how maths has changed over time and can be fun to try!