How_To_Be_Good_At_Math

112 CALCULATING •^ THE GRID METHOD

We can also use a slightly different version of the open

array we saw on page 111. We call it the grid method.

As you get better, the grid can become simpler and

you can find the answers to tricky multiplication

calculations faster.

The grid method

Now we partition 37 into 10, 10, 10,

and 7. Draw lines down the rectangle

between each number. Our rectangle now

looks like a grid.

Next, we partition 37 and 18 into

smaller numbers that are easier to

calculate with. Let’s split 18 into 10 and 8,

and draw a line across the rectangle

between the two numbers.

First, draw a rectangle and label the sides

with the numbers in the calculation:

37 and 18. We can draw the grid roughly,

without using a ruler or measuring the sides.

Let’s use the grid method to work out 37 × 18.

37

37

10

8

18

18

Knowing your multiplication

tables and multiples of 10

will help you to get quicker

at using the grid method.

Split 37 into

10, 10, 10,

and 7

Split 18 into

10 and 8

Label the

sides of a

rectangle with

the numbers

in the

calculation

37 × 18 =?

37

10 10 10 7

10

8

18

112_113_The_grid_method.indd 112 29/02/2016 14:11