83/99 expressed as a percentage is 83.84%. This number tells you how much of a whole the fraction represents when you think in terms of parts per hundred.
The fraction 83/99 is very close to 84 out of 100, so its percentage is just a little under 84%. It’s useful when you need to compare it to other percentages or to see how big a part it is of a total.
You might see this kind of conversion in school reports, sports statistics, or any place where numbers are shown as parts of a whole. Knowing the percentage makes it easier to understand at a glance.