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:

Traditional method

Lattice method

Splitting (grid) method

2 5

51

0 5

2

2 x 5 = 10

5 x 5 = 25

Lattice method – part 125 x 5 = ?

1. Make the lattice (grid) as shown

2. Multiply each number above a column by the numbers in every row3. Write the answers in the lattice. Making sure you have only 1 digit in each triangle

2 5

51

0

51

5

2

2

Add along the

diagonal2 + 0 = 2

Lattice method – part 2 25 x 5 = ?

3 6

82

4 8

4

3 x 8 =24

6 x 8 = 48

Lattice method – part 136 x 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

3 6

82

4

82

8

4

8

Add along the diagonal line4 + 4 = 8

Lattice method – part 2 36 x 8 = ?

3 6

1

3

3 6

1 x 3 = 3

1 x 6 = 6

Lattice method – part 136 x 13 = ?

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

9 81

3 x 6 = 18

3 x 3 = 9

3 6

1

3

3 6

Lattice method – part 236 x 13 = ?

9 8

4 6 8

1

Add along the diagonal line

6 + 1 + 9 = 16

1

Try the questions at the bottom of the worksheets

Grid Method – part 1255 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 = 25This can be placed in a grid

Grid Method – part 2255 x 5 = ?

x200 50 5

200 x 5 50 x 5 5 x 5

5

Finally, add the three numbers together to get your answer.

1000 + 250 + 25 = 1275

 So 255 x 5 = 1 275

1000 25250

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.

Grid Method – part 1255 x 25 = 6375

Put the numbers on the grid

x 200 50 5

20

5

 

Add up each column, then add the resulting numbers together.

Grid Method – part 2255 x 25 = 6375

4000

2501000

1001000

25

4000 + 1000 + 100 = 5100

1000 + 250 + 25 = 1275

6375

Try the questions again using the splitting method

Traditional method 21 x 13 = ?

2 1

x 1 33 x 1 = 3 write down the 3.

36 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

1 02

2 7 3

Traditional method

45 x 34 = ?

4 5

x 3 44 x 5 = 20 write down the 0, carry the 2.

08 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

5 03

5 3 3

1

1

1

1

2

Try the questions again using the traditional method