Adding 3 Two Digit Numbers

Add together two-digit numbers

Learning focus

Larn how to add together two-digit numbers (for example 12 + 27 = 39 or 45 + 23 = 68).

This lesson includes:

one learning summary
1 quiz

Learn

In this lesson we are going to meet how addition, including calculations can exist presented using part-whole models and bar models.

Why not attempt using some items you lot take at domicile to represent tens and ones and practise your own calculations?

Adding two-digit numbers

Example ane

There are different ways to demonstrate additions.

Hither the adding 43 + 32 is shown as a function-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.

Calculations

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

Let'southward take a wait at the calculation 25 + 33.

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

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

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

Now permit's add the 2nd number to the place value chart.

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

Starting with the ones cavalcade first we tin now count everything up to find the answer to the calculation.

There are 8 marbles in the ones column and five sets of pencils in the tens column so 25 + 33 = 58 .

Example 2

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

We tin can write this equally 18 + xi.

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

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

Calculation up the ones column first we can come across there are 9 ones in total.

In the tens cavalcade there are 2 tens then eighteen +11 = 29 .

Example three

Here is a bar model fabricated upwardly of the parts 32 and 26.

This is the aforementioned as 32 + 26 .

Here is 32 + 26 in a place value chart.

In that location are 8 ones and v tens and then 32 + 26 = 58 .

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

Exercise

Activity ane

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

Play

Test your skills on this topic even further past playing Karate Cats Maths - see if you tin collect a new costume for your cat!

At that place's more than to learn

In that location's more than to learn ...

Katie shows some methods for adding two digit-numbers together.

Add 2-digit numbers