 Lesson

## Using patterns to solve addition

When we know the answer to one addition number problem, we can use that to solve other problems. By noticing which digit has changed, such as the tens, we can make a change to our total of the same amount. Do you see any pattern here?

$16+12=28$16+12=28

$26+12=38$26+12=38

$36+12=48$36+12=48

In Video 1, we'll look at how to find number patterns, then use them to find a missing number.

## What if we have to regroup?

If our units add up to 10 or more, we need to make a slight change to how we solve number problems. In Video 2, we look at how we can use regrouping first and then look for a number pattern. We also look at filling in the gap in a number pattern.

#### Worked Examples

##### EXAMPLE 1

$12+13=25$12+13=25

Use this to find:

1. $12+23=\editable{}$12+23=

2. $12+33=\editable{}$12+33=

3. $12+43=\editable{}$12+43=

4. $12+73=\editable{}$12+73=

##### EXAMPLE 2

$13+13=26$13+13=26.

Use this to fill in the gaps in the number sentences.

1. $53+\editable{}=86$53+=86

2. $45+\editable{}=86$45+=86

##### EXAMPLE 3

Complete the pattern below.

1.  $20$20 $\editable{}$ $44$44 $\editable{}$