What is the probability that two people in your class of 30 share the same birthday

The chances that all the birthdays are different:

365! / ((365 - 30)! × 365^30)
= 365! / (335! × 365^30)
=~ 0.293683757280731
=~ 29.3683757280731%

Therefore, the odds that ANY TWO BIRTHDAYS ARE THE SAME are approximately:
1 - 0.293683757280731 = 0.706316242719269 = 70.6316242719269%

Some people might think that the odds are 30 / 365 =~ 0.0821917808219178 =~ 8.21917808219178%, but that is not correct.

I assumed you meant "at least two." If you mean "exactly two but no more," that's MUCH more complicated.

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Question ambiguous.

Did you mean 'exactly 2 and 2 only' or at least 2?
If it is 'at least 2, please read through the source. Replace n with 30.

If it is a class of identical twins then the odds are 1 out of 2.

s why not its possible... it is possible