>>>>Probability of only 1 person having the same birthday is around 0.016% calculated as (364 ^ 23) / (365 ^ 24)
>>>
>>>Where do you get these numbers from?
>>>
>>>Adapting the previous formula, you get:
>>>
>>>1 - (364/365) ^ 1 = 0,27%.
>>>
>>>Which is exactly the same as 1/365.
>>>
>>>Hilmar.
>>
>>Combination of the probability of 1 person having the same birthday (1/365) and the probability of the remaining 23 having a different birthday ((364/365)^23).
>>
>>(Actually, I've got the feeling I'm not totally right, but I can't work out why, but I think it's in the right area).
>
>I think your formula asks whether the first person in an arbitrary list has the birthday on the specific date. To get any person in the list would be more complicated with this approach.
>
>Hilmar.

Calculation is :

0 birthdays the same : (364/365)^24
1 birthday same : 24 * (364^23/365^24)
2 birthdays same : 276 * (364^22/365^24)
3 birthdays same : 2024 * (364^21/365^24)
.....
23 birthdays same : 24 * 364 / 365^24
24 birthdays same : 1 / 365^24

(Originally forgot to apply Pascal's triangle rule to calculation)