The birthday paradox states that if there are 23 people in a room then there is a slightly more than 50/50 chance that at least two of them will have the same birthday. For 60 or more people, the probability is greater than 99%.
Read more to find out how this probability is mathematically possible. In our floor, taking into account 3 main departments, there are at least 33 people altogether. Already, I share the same birthday as one of my colleagues. So there is living proof that this probability is possible.
But, as the article mentions, if you step into a room of 22 people, the chance that someone else shares the same birthday as you is much lower. Out of the 23 people, there are 253 pairs, of which each is a possible birthday match. But if you are looking to share the same birthday as someone in the room, then there are only 22 possible pairs to consider. I have yet to fully comprehend the calculations stated there, tis been years since I touched statistics and probability!
*thanks to kiwlm for the article*