Birthday Paradox Revisited

The answer is that, with in a room, there is a greater than 50% chance that at least two of the people will share the same birthday. If there are 365 people in a room, each with a distinct birthday, there is no way to add another person to the room without them colliding with the date of someone already in the room; every date is taken. When there were four or less people in the room, from my experiments, the non-uniformity of distribution resulted in a slight decrease in the chances of a birthday collision (but this could loss of precision from too small a sample size as the percentage of times, for instance that two people collide is just 0.274%).

Source: datagenetics.com