34/42 expressed as a percentage is 80.95%. This rounded figure gives a quick sense of how large the fraction is compared to a whole.
The fraction 34/42 can be simplified to 17/21, which still represents the same proportion of a whole. Whether you keep it as 34/42 or reduce it, the percentage stays the same.
In everyday situations, you might use this percentage to compare parts of a group, such as 34 out of 42 students who passed a test. Saying that 80.95% passed makes the information easy to understand at a glance.
