51/99 as a percentage is 51.52%. This is the rounded figure you get when you turn the fraction into a percent with two decimal places.
The fraction 51/99 is close to one‑half, but a little bit smaller. If you write it as a decimal, it becomes 0.5151… which repeats. That repeating decimal translates directly to the percent shown above.
In everyday use, you might see this percentage when comparing parts of a whole, like a score of 51 out of 99 points. Remember that the 51.52% figure is already rounded, so the exact value is a tiny bit different, but for most purposes the rounded percent is perfectly fine.
