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 Program
Created by: Chris Cheatham and Maria Farmer WB 2010
Creating a Lattice Grid
The 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 Program
Solving the problem
After 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 problem
Then 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 Program
Created by: Chris Cheatham and Maria Farmer WB 2010