If there are 23 people in a room, what are the odds of two sharing a birthday?

This is a bit retroactive but yesterday, I e-mailed Marco D'Andrea, a first term student to thank him for an invite to his party on July 18 and apologise for not being able to make it (afternoon nap = evening spent doing pressing homework instead of evening = partying with first-term cohort.) 

Turns out that, although he didn't advertise it as such (which would've guaranteed my attendance, homework be damned!), it was his birthday too.  (This revelation also means I now have a better answer to Shea's question of “why would someone have a party on a Tuesday night?” than my original response: “We're college students – we'll party anytime!”.  Man, I'm thick sometimes.)  

So yeah, anyhow, I'm sure we've all heard that if you put 23 people in a room, there's a better than 50% chance that two will share a birthday.  But I think this is the first time I remember knowing someone (other than celebrities and historical figures and so on) who shared my birthday (Marco said he'd never personally known anyone who shared his birthday either.) 

I'm glad to know it's one of the coolest guys in first term too – the first week when a few of us organized a Q&A session followed by a mixer at the Grad Club with the “new kids”, I remember talking to Marco and thinking how awesome he seemed – I mean, how many people do you know who ran a pirate radio station in their undergrad days?  I believe my exact words to Sabina were: “Let's draft him!”

So yeah, Marco gets a very special (and very appropriate) Classmate of the Day nod retroactive to July 18. 

PS – Happy 2nd Birthday, Sawyer.  Too bad you were born on July 21 instead of July 18!

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