Percentages & Simple Interest

What this lesson covers

Percentages & Simple Interest is a 10-part Class 7 Mathematics lesson. Each part makes one point and then hands over to the next, so it can be read in a sitting or picked up again at the part you stopped on. It defines the idea in plain words before using it, works through an example step by step, breaks the topic into its parts and compares them, shows where it is used outside the textbook, names the mistakes that cost marks in an exam, ends with a recap of what to remember.

How it begins

A percentage is a fraction with a denominator of 100. 25% = 25/100 = 0.25 = 1/4Percentages exist so that different totals can be compared fairly. 42 out of 60 and 66 out of 90 are hard to rank at a glance; 70% and 73.3% are not. The essential caution: a percentage always means of something. Without knowing the total, it tells you nothing.

The 10 parts

1. Per cent means out of a hundred
2. The three basic calculations
3. The multiplier method
4. Why a 20% rise then a 20% fall loses money
5. Simple interest
6. A worked interest problem
7. Percentages you will meet
8. Where it usually goes wrong
9. What to remember
10. Watch one worked through