<PRE><B>Question 534256</B>
The probability that one person has a unique birthday is 365/365.&lt;P&gt;
The probability that the second person (justice) doesn&#39;t share the birthday with the first person is 364/365.  There are 364 choices remaining once the day for the first person is removed.&lt;P&gt;
Similarly, each nth person has the probability of a unique date (365-n+1)/365.&lt;P&gt;
Multiply all those probabilities together:&lt;P&gt;

(365*364*...357)/365^9 = 364*363*...357/365^8  (cancel the 365 in the numerator with one 365 in the denominator.&lt;P&gt;

This is the probability nobody shares a birthday.  It&#39;s .9054.  Subtract that from 1 to find the probability that at least two share a birthday.&lt;P&gt;

1-.905376 = .094623 = 9.4623 %</PRE>