Long Multiplication
What is long multiplication?
A number multiplied by a 2 digit
(or larger) number e.g. 25 x 13
Is there only one way to do?
Are there any tips that can help
make it easier?
Methods of Long Multiplication
There are 3 main methods:
Lattice method
Splitting (grid) method
Traditional method
Lattice method – part 1
25 x 5 = ?
5 x 5 = 25
2x5=
10
2
5
1
2
0
5
5
1. Make the lattice (grid)
as shown
2. Multiply each
number above a
column by the numbers
in every row
3. Write the answers in
the lattice. Making sure
you have only 1 digit in
each triangle
Lattice method – part 2
25 x 5 = ?
2
5
1
2
0
1
2
2+0=2
5
5
5
Add along
the
diagonal
Lattice method – part 1
36 x 8 = ?
6 x 8 = 48
3x8
=24
3
6
2
4
4
8
8
1. Make the lattice (grid)
as shown
2. Multiply each number
above a column by the
numbers in every row
3. Write the answers in
the lattice. Making sure
you have only 1 digit in
each triangle
Lattice method – part 2
36 x 8 = ?
3
6
2
4
4
2
8
4+4=8
8
8
8
Add along the
diagonal line
Lattice method – part 1
36 x 13 = ?
1x3=3
3x3=9
3
1x6=6
6
3
6
1
9
8
1
1. Make the lattice (grid)
as shown
3
2. Multiply each number
above a column by the
numbers in every row
3x6=
18
3. Write the answers in
the lattice. Making sure
you have only 1 digit in
each triangle
Lattice method – part 2
36 x 13 = ?
3
6
3
6
1
1
4
9
6
6 + 1 + 9 = 16
8
8
1
3
Add along the
diagonal line
Try the questions at the bottom
of the worksheets
Grid Method – part 1
255 x 5 = ?
First split the number into hundreds,
tens and units.
255 splits into 200, 50, 5
Then, multiply each of the numbers by 5.
200 x 5 = 1000
50 x 5 = 250
5 x 5 = 25
This can be
placed in a grid
Grid Method – part 2
255 x 5 = ?
200
50
5
200 x 5
50 x 5
5x5
x
5
1000
250
25
Finally, add the three numbers together to get your answer.
1000
+ 250
+ 25
So 255 x 5 = 1 275
= 1275
Grid Method – part 1
255 x 25 = 6375
First, split the numbers up.
255 splits into 200, 50 and 5. These go
along the top of the grid.
25 splits into 20 and 5. These go down
the sides.
Put the numbers on the grid
Grid Method – part 2
255 x 25 = 6375
x
200
50
5
20
4000
1000
100
5
1000
250
25
Add up each column, then add the resulting
numbers together.
4000 + 1000 + 100
1000 + 250 + 25
=
=
5100
1275
6375
Try the questions again using
the splitting method
Traditional method
21 x 13 = ?
x
2
1
1
3
3 x 1 = 3 write down the 3.
6
3
2
1
0
2
7
3
3 x 2 = 6 write down the 6
10 x 1 = 10 write down the 10
1 x 2 = 2 write down the 2
Add the numbers
Traditional method
45 x 34 = ?
1
2
x
4
5
3
4
4 x 5 = 20 write down the 0, carry the 2.
1
8
0
1
3
5
0
1
5
3
3
4 x 4 = 16, add 2 write down the 18
30 x 5 = 150 write down the 50, carry the one
3 x 4 =12, add the 1, write down the 13
Add the numbers
Try the questions again using
the traditional method