83/84 as a percentage is 98.81%. This fraction is very close to a whole, which is why the percentage looks almost like 100%.
The decimal form of 83/84 is 0.9881, and when you multiply by 100 you get the percentage shown above.
Because the difference between 84 and 83 is only one part, the fraction represents a tiny shortfall from a full unit.
In everyday terms, 98.81% means that for every 100 items, about 99 are present, and just one is missing.
