18/21 as a percentage is 85.71%. This fraction represents a little less than a whole, and the rounded percentage makes it easy to compare with other values in everyday situations.
The fraction 18/21 can be reduced to 6/7, which still equals the same 85.71% when expressed as a percent. Seeing it as 6 parts out of 7 helps visualize how close it is to a full set.
In real life, you might use this percentage when you’ve completed 18 out of 21 tasks, or scored 18 points on a 21‑point test. It tells you that you achieved about 86% of the total, giving a clear picture of performance without needing exact fractions.
