The fraction 66/78 as a percentage is 84.62%. This value tells you how close the fraction is to a whole when it is expressed in parts of 100.
The numbers 66 and 78 share a common factor, so the fraction can be reduced to 33/39, which still represents the same proportion. Whether you look at the original or the reduced form, the portion of the whole remains the same.
In everyday situations, you might see 84.62% used to describe a test score, a success rate, or any other scenario where a part of a total is expressed as a percent. Rounding to two decimal places keeps the figure clear and easy to work with.