Transcript Multiplying large numbers - lattice method

Multiplying large
numbers - lattice
method
Created by: Sabrina Edmondson
Adapted from BBC online
Multiplying large numbers
- lattice method
This method is also called
Napier's bones.
In some ways it is similar to the grid
method as it involves multiplying rows and
columns, but it gives you a better way to
add the results at the end of the
calculation.
Multiplying large numbers
- lattice method
With this method, you multiply each
number in the column by each number
in the row. Then you add along the
diagonals to get the answer.
Have a look at this equation:
25 x 5
Multiplying large numbers
- lattice method
Step 1:
Make a grid with
diagonal lines as
shown below. Split
the 25 into a 2 and a
5, putting each digit
at the top of a
column. Put the 5 by
the top row.
25
Multiplying large numbers
- lattice method
Step 2:
Multiply the
columns by the
rows, splitting the
digits up on either
side of the
diagonal as shown
here.
Multiplying large numbers
- lattice method
Step 3:
Finally, add
along the
diagonals to get
your answer.
So: 25 x 5 = 125
Multiplying large numbers
- lattice method
This method is a bit complicated.
Talking yourself through each step as
you do it can be useful - someone is
sure to ask you what you're doing and
you'll end up explaining to them!
Multiplying large numbers
- lattice method
Let’s look at another multiplication equation
worked out using the lattice method.
With this method, you multiply each number in
the column by each number in the row. Then you
add along the diagonals to get the answer.
Have a look at this equation:
25 x 5
Multiplying large numbers
- lattice method
Step 1:
Make a grid with
diagonal lines as
shown. Split the 255
into 2, 5, and 5,
putting each digit at
the top of a column.
Split the 25 into 2
and 5, putting each
digit by a row.
255
25
Multiplying large numbers
- lattice method
Step 2:
Multiply the
columns by the
rows, splitting the
digits up on either
side of the
diagonal as shown
here.
and 4 ones
Multiplying large numbers
- lattice method
Step 3:
Finally, add
along the
diagonals to get
your answer.
So: 255 x 25 = 6375