2. Addition and subtraction

Lesson

Do you remember how to make a target number ?

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

We can use number lines to make a target number by plotting the beginning number and the target number, and counting how many spaces are between them.

For our number sentences to be equivalent, both sides need to be equal. Let's see how to check if this is true, as well as how we can make it true.

Complete the number sentence: 31 - ⬚ = 16

Worked Solution

Idea summary

We can use number lines to make a target number using subtraction by plotting the beginning number and the target number, and counting how many spaces are between them.

If we need to find a missing number, we can use things such as bridge to 10, and number lines to help us. Let's see how we can do this for an addition and a subtraction problem, to make a sentence equal.

Complete the number sentence: 48 - ⬚ = 19 + 16

Worked Solution

Idea summary

For number sentences to be equivalent, or balanced, both sides must equal the same amount.

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