Long Multiplication

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 125 x 5 = ? 5 x 5 = 25 2 x 5 = 10 1. Make the lattice (grid) as shown 1 2 0 5 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 = ? 1 2 0 5 1 2 5 Add along the diagonal 2 + 0 = 2

Lattice method – part 136 x 8 = ? 6 x 8 = 48 3 x 8 =24 1. Make the lattice (grid) as shown 2 4 4 8 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 = ? 2 4 4 8 2 8 8 Add along the diagonal line 4 + 4 = 8

Lattice method – part 136 x 13 = ? 1 x 6 = 6 1 x 3 = 3 1. Make the lattice (grid) as shown 3 6 3 x 3 = 9 2. Multiply each number above a column by the numbers in every row 1 9 8 3. Write the answers in the lattice. Making sure you have only 1 digit in each triangle 3 x 6 = 18

Lattice method – part 236 x 13 = ? 3 6 1 1 9 8 4 6 8 Add along the diagonal line 6 + 1 + 9 = 16

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 = 25 This can be placed in a grid

x 200 50 5 200 x 5 50 x 5 5 x 5 1000 + 250 + 25 = 1275 5 Grid Method – part 2255 x 5 = ? 1000 250 25 Finally, add the three numbers together to get your answer. So 255 x 5 = 1 275

Grid Method – part 1255 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

Then, multiply each number in the column by each number in the row. Have a look at the grid below. x 200 50 5 20 5 Grid Method – part 2255 x 25 = 6375 4000 1000 100 1000 250 25 Add up each column, then add the resulting numbers together. 255 x 25 = 6 375

Try the questions again using the splitting method

Traditional method 21 x 13 = ? 3 x 1 = 3 write down the 3. 6 3 3 x 2 = 6 write down the 6 10 x 1 = 10 write down the 10 2 1 0 1 x 2 = 2 write down the 2 3 7 2 Add the numbers

Traditional method 45 x 34 = ? 1 2 4 x 5 = 20 write down the 0, carry the 2. 1 8 0 4 x 4 = 16, add 2 write down the 18 30 x 5 = 150 write down the 50, carry the one 1 3 5 0 3 x 4 =12, add the 1, write down the 13 3 3 5 1 Add the numbers

Try the questions again using the traditional method

Long Multiplication