Are you looking for information on grid method multiplication? Multiplication is a skill you’ve been working on since primary school and is probably one of the most important skills you will need on your non-calculator paper. This blog focuses on just the multiplication of positive numbers, including decimals. It does include some addition and subtraction as these regularly come up in the same question.

In this series of blogs, we are going to look at three different methods for multiplication – it’s usually best to stick to the method you know but, if you are struggling, try one of the other methods.

For this method, partition each number into groups to make it easier to multiply. In most cases, that means splitting into hundreds, tens, ones, tenths and so on. So, 72.4 becomes 70 + 2 + 0.4 and 8.14 becomes 8 + 0.1 + 0.04.

We arrange these numbers round the outside of the grid and multiply each section in one number by each section in the other number:

Finally, we find the sum of the numbers in the grid.

So, 72.4 × 8.14 = 589.336

Example 2 Tony is buying a new motorbike. He pays a deposit of £1256 and then pays the remainder of the cost in 18 payments of £237 each. Find the total cost of the motorbike.

First, we will find the total amount paid in the 18 payments. To do this, we will calculate 237 × 18.

So, the 18 payments of £237 total £4266. We need to add this to £1256 to find the total amount spent:

So, the total amount Tony spent on the motorbike is £5522.