Same birthday probability Calculator

Calculates the probability that one or more pairs in a group have the same birthday.

Same birthday probability
n
    1. persons
    2. in a group

    1. Probability with same birthdays
        p(n)
    1.  
    2. %
(1) the probability that all birthdays of n persons are different.


(2) the probability that one or more pairs have the same birthday.


This calculation ignores the existence of leap years.
    Same birthday probability
    [1-2] /2Disp-Num
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    [1]  2017/12/05 06:36   Female / 40 years old level / Others / A little /
    Purpose of use
    Settling an argument.
    Comment/Request
    In a random sample of "n" people, 2 are found to share the same birthday.
    In a second random sample of people, 2 are found to share the same birthday.
    What are the odds that both pairs of people share the same birthday?
    [2]  2009/07/30 02:00   Male / More than 60 / Others / Very /
    Purpose of use
    Very useful for backing up a bet taken in a pub. Thank you - I won.
    Comment/Request
    I love this kind of "dispute" settler - in addition, the formulae are beautifully complex in appearance, so my non-maths friends are entirely bamboozled.

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