45/85 as a percentage is 52.94%. This rounded figure gives a quick sense of how large the fraction is compared to a whole.
The fraction 45/85 can also be thought of as 45 parts out of 85 equal parts. Seeing it as a percentage makes it easier to compare with other numbers that are already in percent form.
When you need to use this value in a report or a presentation, just write 52.94% and it will be understood by most readers without any extra calculation.
Remember, rounding to two decimal places keeps the number clear and precise enough for most everyday purposes.
