2. Addition and subtraction

Lesson

Do you know how to count on from a number?

Complete the pattern by adding 2 each time. 40,\, 42, \, 44, \, ⬚, \, ⬚, \, ⬚

Worked Solution

Idea summary

We can count on from a number by adding the same amount repeatedly to that number.

To find out the difference between two numbers, we can jump from our starting number to our target number, like we do in this video.

Find the missing number to equal the number 98.

a

89 + ⬚ = 98

Worked Solution

b

20 + ⬚ = 98

Worked Solution

c

28 + ⬚ = 98

Worked Solution

Idea summary

To find how much we need to add to one number get to another number, we can plot both numbers on a number line and count the spaces between them.

Sometimes we can solve a problem, and then use that to find a pattern in addition or subtraction. Watch this video to see how.

113+20=133. Use this to find:

a

113 + 30 = ⬚

Worked Solution

b

113 + 40 = ⬚

Worked Solution

c

113 + 50 = ⬚

Worked Solution

Idea summary

If we notice a pattern in our problems, it can make it much easier to solve other problems. We can use place value to see what has changed and then focus on that in other problems.

uses mental and written strategies for addition and subtraction involving two-, three-, four and five-digit numbers

generalises properties of odd and even numbers, generates number patterns, and completes simple number sentences by calculating missing values