Suppose there are n people, and the probability that at least two people have birthdays on the same day exceeds 0.5.

There are:

N people have birthdays, so everyone has any day in 365 days.

So the possible situation of n people should be 365 n (365 n power)

Assuming that n people no longer have birthdays on the same day, it should start from 365 days.

Optional n days, that is, A(365, n);

So the probability that n people will no longer have birthdays on the same day should be:

A(365,n)/(365^n)

In other words, at least two of n people have birthdays on the same day.

The probability should be:

1-A(365,n)/(365^n)

According to the requirements, 1-A(365, n)/(365 n) >: =0.5.

According to the above, n=23 can be obtained.

Because the calculation is more troublesome, I will leave it alone.

I'm sorry/sorry/I feel bad/I can't wake myself up. ...