Blog Post #40: Prize Competition, end-of-March Birthday Brainteasers for You!!

Dear Readers,

Though many of us have never met each other in person yet, to everyone whose birthday is either today or still coming this month, I wish you all a wonderful time, along with the friends starring in this article, number forty!

To celebrate, I have decided to offer a nice prize (a surprise!) to whoever sends me what I consider to be the very best, well-explained solution to the brainteaser puzzles in today’s article.

To enter the competition, you should send me your solution, presented neatly, by e-mail to, but without e-mail attachments.

The closing date is Easter Monday, 2 April 2018. The winner will be announced on my site by Friday 6 April next week, and will also be notified by e-mail to congratulate him or her personally.


Earlier today, I messaged Jane and Alex, friends who have their birthdays tomorrow. I also thought of Julia, a friend and former colleague whose birthday is on the same day as that of David, a retired minister who is the father of another friend and former colleague! Last, but certainly not least, I remembered Ingrid–a friend whose birthday is actually before Julia and David’s birthday–and I will contact Peter and Yen whose birthdays are later. There are so many happy birthdays to celebrate that we almost need 32 days in the month!


If I multiply together the March birthday day numbers of David, Ingrid and Julia, and then divide by 32, I still get a whole number result. Your fun brainteaser is to figure out that whole number precisely, and the March birthday day numbers of Ingrid, David and Julia.

The brainteaser can be completely solved using only the information given in this article.


Suppose that Jane and Alex were to multiply their new ages together tomorrow and then add on both of their new ages. Subtract that result from the product of their ages next year (on their birthdays on 27 March 2019). What is the final result?

I look forward to receiving some excellent mathematical solutions, and to announcing a winner next week. In the meantime, please do have lots of fun with the puzzles!

Wishing everyone a very happy Easter,

Paul Motwani.

Author: Paul A. Motwani

My name is Paul Motwani, but my colleagues, my students and their parents mostly call me "Mr. Mo"! My middle initial, A, stands for Anthony, because I was born on the official feast day of St. Anthony of Padua, the patron saint of miracles and of lost souls. I love teaching Mathematics and Chess, and giving fun-packed talks and shows in schools and clubs. The popular ingredients of Math, Chess, Mystery and Magic are my "Fantastic Four", and I give prizes too! I am an International Chess Grandmaster, and (loooooong ago!) I was the World Under-17 Champion. I am the author of five published chess books and hundreds of newspaper articles. I live with my wonderful wife and son in Belgium. I also love music, movies and puzzles. I blog at My e-mail address is You can find me on Facebook, too.

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