Sabih's Recreational Mathematics Page


In my high school and student years (late seventies to early eighties) recreational mathematics was one of my hobbies. Nowadays I hardly spend time on this hobby. Via this page, I have the intention to present topics that attracted my attention in the earlier as well as more recent past.

The Memory Game

In 1983, I had the opportunity to combine my interest in recreational mathematics with a project that was part of the electrical engineering curriculum: the 65-afternoon project. It turned out that Dr. Frits Göbel was looking for a candidate to analyze the memory game. I liked the topic and accepted to carry out the project.

I, of course, documented the results of that project in a report (written in Dutch). In those days, text processing was not yet very common and handwritten reports were perfectly acceptable. I only posses a "2-up" photocopy of that report, which I have scanned. It can be downloaded in parts using the links below:

My interest in the topic reawakened after reading the October 1991 issue of Scientific American. It reported about the memory game and similar results as obtained in my project. I managed to contact the main researcher, Uri Zwick. A pleasant correspondence followed. At one occasion I sent him my 65-afternoon-project report accompanied by a summary in English. Once he learned about the essence of our work, he kindly managed to add some sentences on our work to the article on the memory game that was already accepted for publication in the journal Theoretical Computer Science.

A Remarkable Recruitement Ad

In June 2009, I ran into a recruitement ad of a company called Optiver starting with the following text:
How many ways are there of distributing n coins among x people, so that everybody gets at least one coin?

The coins are exactly the same, however each person is unique. Therefore giving two coins to the first person and 1 coin to the second person is different than giving 1 coin to the first person and 2 coins to the second person.

If you enjoyed solving the little puzzle, you might be interested in our vacancy for a Quantitative Researcher, which has arisen in our Research team due to the company's growth.

and ending with:
Interested? Apply directly via our Apply now button. Please include your solution to the puzzle at the top of the ad, together with an explanation of how you got there. Also, state the result for n=11, x=3.
I found the problem sufficiently challenging to try to solve it in an elegant way. You can download my solution, if you want.
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Last update on: Tue Oct 15 00:41:49 CEST 2019 by Sabih Gerez.