Without Googling.......

[ToraToraTora]

How many people need to be in the same room for there to be an even chance of sharing a birthday month and day? The answer may surprise you.

[spathiphyllum]

1

[bookbinder]

3

[Mamyalynne]

I read the other thread, so won't reply.

[andres]

13

[Kathyan]

Not an answer, but I was at an ice hockey game once with a crowd of over 9000 and I was sat next to a stranger. We got talking and it turned out that we had the same Birthday!

[johnny.5]

8?
total guess

[Buenchico]

23, which I didn't need to Google - but only because I remember it from teaching A-level maths ;-)

[ToraToraTora]

yest chris, didn't realise this was mentioned in another thread. Often when you ask this people say 180 or some such thing.

[Mamyalynne]

It was mentioned here...

https://www.theanswerbank.co.uk/News/Question1654476.html

[Peter Pedant]

// I read the other thread, so won't reply.//
your honesty mama will do you no good at all on the AB site

[ wow sounz a bit - apocryphal, innit? fiery even]

[Mamyalynne]

My honesty is my concern , but thanks.

[Peter Pedant]

oh......so you do

[spathiphyllum]

Why 23?

[Mamyalynne]

Exponents.

https://en.wikipedia.org/wiki/Birthday_problem