Thursday, April 2, 2015

B is for . . .

Do you hate math? Know someone who is great at math? Usually it's one or the other. This month I'm posting some Mad-Cool-Math Nuggets. Maybe it'll make you think twice about numbers.

Image courtesy: 4rank

B is for The Birthday Paradox.

They say it's your birthday! It's my birthday too, yeah!

There are around 7 billion people on the planet and only 366 (including Feb. 29) days in the year. Even if you can't do the math, obviously you're sharing your birthday with lots and lots of people. Still, would it surprise you to know that in a group of just 23 randomly chosen folks, the probability that two share a birthday is

(a) 10%
(b) 20%
(c) 30%
(d) 40%
(e) 50%

Answer: e

That's right. Are you a writer? Go ahead those two star-crossed lovers who meet in a bar the same birthday.

Want to know why? I'll send you here for a YouTube Video to provide a general idea and here for an article on actually calculating the odds.

There are birthdays that are more popular than others. For Americans between 14 and 40, the most common is September 16. In fact, September is the biggest birthday month (which means Christmas time is the biggest . . . ah hem, time for something else). Check out this chart.

When I went to Flickr to pick out an image for this blog, my top choice, as seen above, was snapped on my birthday! Maybe I shouldn't be surprised.

What month is your birthday? Have you heard about the Birthday Paradox? Do you know who sings The Birthday Song with the lyrics above?


  1. That's so crazy! I had no idea the odds where that high. But then my in-laws share a birthday, as well as my step grandparents, so, you know.

    Good luck with the 2015 A to Z Challenge!
    A to Z Co-Host S. L. Hennessy

  2. The Beatles sang that version of The Birthday Song.

  3. I was born on my grandfather's birthday, September 2nd. I agree with Melanie, it was The Beatles that sang The Birthday Song. Love your blog! Thanks for stopping by

  4. Very cool post! I had no idea that shared birthdays were so common, but thinking about it does make sense!

  5. That was fascinating. I am so not a math person but I did give birth 3 times on a June 22. My kids have the same birthday. Obviously I couldn't wait til Christmas...

  6. I love maths, so does my hubby and one of my girls. Interesting about birthdays. Great theme.
    Rhonda ~ a LiveWire too.

  7. Hi Tamara! I'm thrilled that I finally found a few moments to visit my fellow Minions and Live Wires. :D So happy to 'meet' you.

    My birthday is in August and was born on Friday the 13th of all days. Sheesh. I can't say that I've ever heard of the Birthday Paradox, but thanks for sharing. I love learning interesting tidbits of information. I'm with Doreen, so not a math person. :D

    I look forward to checking out more of your posts. It's going to be an interesting month! Have a great day. Eva

  8. My birthday is in July and, no, I never heard of birthday paradox.
    Evalina, This and that...

  9. Wow...I shouldn't be surprised though.Look at these ... My ex B.i.L & I shared the day, my eldest son and his paternal grandma, my stepson and his half-sister via his Mama, plus too many cousins that match up to count. I just thought our family liked to play on the same nights of the years! Thanks for the education!


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