99/990 = 10%
A value like 99/990, or 10%, can show up in everyday situations such as a store discount, a test score, or a service fee. For example, a 10% discount means about ten dollars off a $100 purchase.
You can picture 10% as one part out of ten equal parts. It is also easy to estimate by moving the decimal point one place to the left, so 10% of 70 is about 7.
A common mistake is confusing 10% with 10 percentage points. A change from 40% to 50% is an increase of 10 percentage points, but it is a 25% increase compared with the original 40%.
