Number (add/sub)

Hong Kong

Stage 1

Lesson

Here we're going to look at how we can make numbers by adding or taking away.

If we add two numbers together we are going to make a bigger number.

If we start with a number and take away we are going to make a smaller number.

When we add large numbers we can break them down into tens and units to make our job easier.

So if we're adding $64$64 to a number, we can make it easier by breaking it down and adding $10$10, $10$10, $10$10, $10$10, $10$10, $10$10 and $4$4!

This makes our job of adding easier, we can also work backwards, adding $6$6 tens and $4$4 units means our starting number and landing number are $64$64 units apart, $10+10+10+10+10+10+4=64$10+10+10+10+10+10+4=64.

Let's take a look at how we can make new numbers by adding or taking away.

Use the sliders below to try making some numbers by adding!

Try taking away below!

Choose the numbers that make $64$64 from the list below. There may be more than one correct answer.

$46+18$46+18

A$79-15$79−15

B$66-4$66−4

C$69+4$69+4

D

Use the numbers to answer the questions below.

$30+16$30+16

$21+22$21+22

$16+27$16+27

$48-5$48−5

Identify the target number that 3 of the 4 groups of numbers make.

What is the target number of the odd one out?

How can we change the sum of the odd one out ($30+16$30+16) to make it match the target number $43$43?

$30+16-3$30+16−3

A$30+16+3$30+16+3

B$30+16+2$30+16+2

C

Let’s play a game called target number. Here’s how it works. I give you a target number and starting number and you tell me what I need to get there.

For example, our target number is $96$96, and if I tell you the number $95$95 you would say $1$1, because $95+1=96$95+1=96.

Find the missing number below for our target number $96$96.

$93$93$+$+$\editable{}$$=$=$96$96

$25$25$+$+$\editable{}$$=$=$96$96

$56$56$+$+$\editable{}$$=$=$96$96