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How can we show addition?

There are different ways to demonstrate additions.

Let's take a look at this calculation:

43 + 32

We can also show this as a part-whole model and a bar model.

Each way of showing the calculation shows part + part = whole.

75 is the whole number and 43 and 32 are the parts.

When a number is made up of more than one digit we can use a place value chart with headings, like ones, tens, hundreds and thousands, to help us understand the value of each digit.

Let's take a look at the calculation 25 + 33.

Using a place value chart to work out the answer to this calculation we split each number into tens and ones.

Each packet of pencils represents one ten and each marble represents one in the ones column.

25 has 2 tens and 5 ones so we add 2 packets of pencils to the tens column and 5 marbles to the ones column.

Now let's add the second number to the place value chart.

33 has 3 tens and 3 ones so we add 3 packets of pencils to the tens column and 3 marbles to ones column.

Starting with the ones column first we can now count everything up to find the answer to the calculation.

There are 8 marbles in the ones column and 5 sets of pencils in the tens column.

25 + 33 = 58

Example 1

Let's take a look at this part-whole model and work out what the whole is.

We can write this as

18 + 11

As with the other example we will use a place value chart to work out the answer.

Here we have 1 set of pencils and 8 marbles on top representing 18 and 1 set of pencils underneath and 1 marble representing 11.

Adding up the ones column first we can see there are 9 ones in total.

In the tens column there are 2 tens.

18 +11 = 29

Here is a bar model made up of the parts 32 and 26.

This is the same as 32 + 26.

Here is 32 + 26 in a place value chart.

There are 8 ones and 5 tens.

32 + 26 = 58

When you're working out additions using these methods, always add up the numbers in the ones column first.

Have a go at the questions in this quiz. You can use a piece of paper to draw a place value chart if it helps with your working out.