21/90 as a percentage is 23.33%. This number comes from turning the fraction into a familiar form that’s easy to compare with other values. It tells you that 21 out of every 90 parts is a little less than a quarter.
The fraction 21/90 can also be simplified to 7/30, which is still the same amount. Whether you write it as a fraction or a percentage, the value stays the same, just expressed in a different way.
In everyday use, rounding to two decimal places makes the percentage clear and quick to read. So when you see 23.33%, you know it represents the same portion as 21 out of 90 parts.
