34/42 expressed as a percentage is 80.95%. This rounded figure gives a clear sense of how much of a whole the fraction represents.
The fraction itself can be simplified to 17/21, but the percentage stays the same. Seeing the number as a percent makes it easier to compare with other values, like grades or test scores.
In everyday use, you might say that something is about 81% of the total. That quick estimate is handy for budgeting, cooking, or any situation where you need a fast, understandable number.