Lattice Multiplication

Lattice Multiplication is an alternative method for solving multi-digit multiplication problems.

Many students enjoy this method because it helps them keep track of their partial products without having to add extra zeros and it reinforces the use of their basic facts.

Information from the Algorithms Handbook of the Everyday Math ProgramCreated by: Chris Cheatham and Maria Farmer WB 2010

Creating a Lattice GridThe size of a lattice grid depends on the size of the factors that you are multiplying.

One factor goes along the top of the grid. If it is a two digit number the grid will have 2 columns. If it is a 3 digit number you will have 3 columns in your lattice grid.

The other factor goes down the right side of the grid. If it is a two digit number the grid will have 2 rows. If it is a 3 digit number you will have 3 rows in your lattice grid.

Information from the Algorithms Handbook of the Everyday Math ProgramCreated by: Chris Cheatham and Maria Farmer WB 2010

Solving the problemAfter you have constructed your lattice grid you will begin multiplying the factors.

Begin with the first digit from the factor on the side and move your way to the left by multiplying that digit with the digits from the factor on the top.

Each answer goes into its own cell. The tens digit goes above the dotted line and the ones digit goes below the dotted line within the cell.

If an answer does not have a number in the tens place you need to remember to write a zero in the tens place of that cell.

Created by: Chris Cheatham and Maria Farmer WB 2010

Solving the problemThen you move to the next digit of the factor that is on the side of your lattice grid.

Following the same steps that you used with the first digit move to the left multiplying this digit with the digits of the factor on the top of your lattice grid.

Created by: Chris Cheatham and Maria Farmer WB 2010

Solving the problem

Now that you have your lattice grid complete your next step is to add your partial products together.

Add along each diagonal beginning with the bottom right diagonal. Work towards the upper left diagonal. If necessary regroup each tens digit to the top of the next diagonal.

Information from the Algorithms Handbook of the Everyday Math ProgramCreated by: Chris Cheatham and Maria Farmer WB 2010