9/80 = 11.25%
A value like 11.25% can show up as a discount on a store item, a fee added to a bill, or the share of a group that chose a particular option. It is a little more than one-tenth, so it is noticeable without being a large part.
To picture it quickly, imagine 100 equal squares: a bit more than 11 of them would be shaded. You can also think of it as close to 10%, with a small extra amount.
One common point of confusion is treating 11.25% as the same as 11.25, even though a percent describes a part out of 100. It is also easy to mistake it for 11.25 percentage points, which is a way to describe the difference between two percentages.
