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So if there are 7,632,819,325 people currently alive (According to google), then how many of those people are "One in a million"? My math behind it was to divide the number by a million, but I just wanted to double check. I got the number 7,632; as expected- but this felt a little too easy. (Math has never been my strong suit, lol.) Thanks!

Gracie-Previelle
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    That depends on your definition of "one in a million." In a million people, one of them may be the fastest, one of them may be the smartest, one of them may be the tallest, etc... you could potentially come up with a million different superlatives to quantify them by at which point they are all "one in a million." – JMoravitz Jun 22 '18 at 20:43
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    If you are referring to something more along the lines of "among a million people, only one is expected to be taller than a certain height" at which point, yes, among the total population of the world there would indeed be an expected $7,632$ people that are taller than that height. – JMoravitz Jun 22 '18 at 20:44
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    According to the Discworld books by Terry Pratchett, one in a million chances come through nine times out of ten. So, the number of one in a million people is 6,869,537,393 – Will Jagy Jun 22 '18 at 20:46
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    “Scientists have calculated that the chances of something so patently absurd actually existing are millions to one. But magicians have calculated that million-to-one chances crop up nine times out of ten.” – Will Jagy Jun 22 '18 at 20:50
  • Statistically it should be between 7489 and 7777 at 90% confidence. – Joffan Jun 22 '18 at 20:55
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    Each of those people is "one in 7,632,819,325". And that is much rarer than one in a million. – GEdgar Jun 22 '18 at 21:24

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For a single trait for a human to possess such that the odds of a single person possessing that trait are "one in a million", then the expected number of people globally to possess that trait would be around 7,632 as you state. But, that is just the expected number. Since this would be a binomial distribution, you are likely to come close to that number, but if you wanted a 95% confidence interval, it would be more like you can be 95% confident that between 7,463 and 7,809 people are "one in a million".

SlipEternal
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