 It is not a coincidence that ; a similar approximate pattern can be found using a number of possibilities different from 365, or a target probability different from 50%.Another generalization is to ask for the probability of finding at least one pair in a group of people with birthdays within calendar days of each other, if there are equally likely birthdays.The number of people required so that the probability that some pair will have a birthday separated by days or fewer will be higher than 50% is given in the following table