What is Lattice?​

Lattice Multiplication is a way to multiply multidigit numbers using a series of boxes. For each digit of a number you will need a a row or column.

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Setup

Once you have your boxes made for your numbers you will need to make diagonal line through each box going from the top right to the bottom left. Each diagonal line will represent a different place value.

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Step One

​Select a square from inside the ​lattice box you have made. Find the number that is directly above that box and the number that is to the right or left of that box. Both numbers will come from outside of the lattice diagram

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Step Two

​Multiply the numbers and place the product in the square you selected earlier. The tens digit of the product is in the triangle on the left and the ones digit is in the triangle on the right. If there is no digit for the tens place put a zero in the left triangle

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Step 2 continued

Continue this with each square until every triangle has a number in it.

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Step 2 Completed

When you are finished each triangle should have a number in it and it should look like the image on the right.

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Step 3

Now you will use the diagonal lines. Each diagonal line separates a place value. Add each number of that place value together.

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The Answer!

Once all the numbers are added together you have your answer. It should look like this​

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Carrying When Adding

Sometimes you will get a two digit number while adding your diagonal numbers. When this happens carry the number in the tens place of your sum to the next set of diagonal lines you will add. On the image to the right you can see the sum of 8, 4, and 5 is 17 so they carried the 1 to the next set of diagonal numbers and they will add it there.