GST in Australia is 10%, which means one tenth of the price. To add GST, find 10% of the price and add it to the original. For $80, 10% is $8, so the price with GST is $80 + $8 = $88. Finding 10% is easy: divide by 10. Remember the two steps — work out the GST, then add it, so the total is bigger than the start.
Explore this idea with maths tools
Maths you can move
Build 8 + 5
Tap two gold counters to fill the ten-frame.
8 in the frame + 5 waiting. The total stays the same.
Words to know
- GST
- Goods and Services Tax, 10% added to most prices in Australia
- per cent
- out of 100; 10% means 10 out of every 100, or one tenth
Worked examples
Add 10% GST to $80
- 1.10% of $80 = $8.
- 2.$80 + $8 = $88.
= $88
Add 10% GST to $150
- 1.10% of $150 = $15.
- 2.$150 + $15 = $165.
= $165
Add 10% GST to $45
- 1.10% of $45 = $4.50.
- 2.$45 + $4.50 = $49.50.
= $49.50
For parents
Method: Divide by 10 for the GST, then add.
What to say: Ask 'what is one tenth of the price?' then 'now add it on.'
Common mistakes:
- Giving just the GST amount, not the total.
- Adding a flat $10 instead of 10%.