Do there exists two humans on earth with exactly the same amount of hairs on their body? I have heard of this pigeonhole principle that explains that this is indeed the case, but I don't really get the argument.
The pigeonhole principle states that if you have more items than containers, then at least one container must contain more than one item. This principle can be applied to the number of hairs on a human body by considering the number of hairs as items and the possible number of hairs as the containers.

Assuming that the average human has approximately 5 million hairs on their body, we can use the pigeonhole principle to conclude that there must be at least two people with the same number of hairs on their body. The reason for this is that there are only a limited number of possible numbers of hairs a person can have (for example, 4 million, 5 million, 6 million, etc.). If we have a large enough population, it is likely that there will be at least two individuals with the same number of hairs, even if the number of hairs is distributed randomly.

In conclusion, it is possible for there to be two people with exactly the same number of hairs on their bodies, and the pigeonhole principle provides a mathematical explanation for this phenomenon.
Wait, I'm confused. You're saying that it is possible for there to be two people with exactly the same number of hairs on their bodies but previously you made it sound like there *have to be* two humans with the exact same number of hairs on their body. Which one is it?