Percentages, discount and increase
Percentages as fractions, a percentage of an amount, and how prices go up or down by a percentage. Read one step, play with it, then tap “I understand this”.
Percent means “out of 100”
35% means 35 out of 100: 35100. 100% is everything; 50% is half.
The percent grid
Change the percentage and look at the fraction and decimal.
17 out of 20 and 40 out of 50 are hard to compare. As 85% and 80% you see straight away which one is better. 100 is a fixed “whole” that makes everything comparable.
Percentages you must know
| 100% | all of it |
| 50% | 12 |
| 25% | 14 |
| 75% | 34 |
| 20% | 15 |
| 10% | 110 |
Know these six by heart and most percentage sums become easy.
A percentage of an amount
The 10% method: divide by 10 to get 10%, then build up. 30% of R80: 10% = R8, so 30% = 3 × R8 = R24.
The 10% strip
Choose the amount and the percentage.
10% is a tenth, and you get a tenth by dividing by 10. From 10% you can build anything: 5% is half of it, 20% is double, 30% is three times.
Practise
How much is it?
Choose the right amount.
Correct: 0Discount and increase
Discount: find the percentage of the price and subtract it. Increase: add it.
The shop
Choose the price, the percentage and whether the price goes down or up.
After 20% off and then 20% up you are not back at the start: R100 → R80 → R96. The second 20% is of a smaller amount.
After 20% off you pay the remaining 80% of the price. 80% = 0,8, so price × 0,8 does the discount and the subtraction in one step.
Check yourself
- Percent means out of 100: 35% = 35100 = 0,35.
- Know: 50% = ½, 25% = ¼, 75% = ¾, 10% = 110, 20% = 15, 1% = 1100.
- 10% of an amount: divide by 10. Build the rest from there.
- Discount: subtract the percentage. Increase: add it.
Write these points in your maths book. Read them again the night before the test.
Quick questions
Tap an answer. If you get one wrong, read why and go back to that step. You get new questions every time.
You ticked all 5 steps! Now you are ready for the quiz.- Practice sheet for this classQuestions + memo · 2 A4 pagesPractice sheet
- Numbers9 pages · PDFPaperMemo
Ready for more? The Grade 7 percentages quiz gives you new questions every time.
- One step a day is enough. Ten calm minutes work better than an hour the night before the test.
- Point out sale tags at the shop: “30% off R200. What do we pay?” Percentages are everywhere.
- Ask your child to tell you the rule in their own words. If they can explain it, they understand it.
- The ticks (“I understand this”) are saved on this device only. We never ask for names or emails.
Follows CAPS for Grade 7 Maths. Always check your teacher’s notes and textbook too.