Theoretically, the chances of two people having the same birthday are 1 in 365 (not accounting for leap years and the uneven distribution of birthdays across the year), and so odds are you’ll only meet a handful of people in your life who enjoy the same birthday as you. This leads many people to intuitively guess around 180.
The correct answer is just 23.
That means in each of your classes at school, amongst the fellow commuters on the bus to work and amongst the players on a soccer field, there are more than likely at least two people with the same birthday.