About 30 in every 200,000 people get a perfect GMAT score. It is highly unlikely that they are all students; Several are probably GMAT tutors.
Practically speaking, to get an 800 on the GMAT, you have to score a perfect 51 in Quant and a perfect 51 in Verbal. That does not mean you can't miss a single question. You may be able to miss a difficult question, but you definitely can't miss any easy questions! The reason: Your score is calculated based on the difficulty level of the questions you get correct and incorrect. You may even be able to get an 800 with a 50/51 in one of the sections.
You do not need to score 99th percentile in math to get an 800. In fact, it's not even possible to get a 99th percentile score in math! A perfect 51 is a 97% or a 98% depending on the data. The reason: Many nonnative English speakers who excel in math take the GMAT and get perfect (or at least very high) scores. This skews the quant and verbal percentiles. You will however need to score 99th percentile in Verbal to get an 800, since 99th %ile amounts to a Verbal score of about 45/51.
Your Integrated Reasoning and Essay scores are separate scores and do not count toward your 800 score.
Do you need a perfect score to get into a top business school? Definitely not! You don't even need 99th percentile. You do, however need to have a competitive application profile. Depend on the rest of your profile, that may mean scoring above average for the schools your targeting. For the top 10s, that means scoring 730+. You may not be targeting top 10s and might be fine with a different score.
We will help you set realistic targets and work toward them in a very efficient way. Contact us if you're ready to get help.