By Susam Pal on 16 May 2026

Let me share a very silly story from roughly 18 years ago! In 2008, I joined RSA, the network security company named after the initials of the inventors of the RSA algorithm, Rivest, Shamir and Adleman, who were also the founders of RSA, the company.

There was a bit of a nerd culture in the workplace where topics like prime numbers, combinatorics, probability theory, etc. were discussed fervently. A prime-number employee number was considered a lucky charm. I had a rather nice large five-digit prime number as my employee number, which I remember being quite pleased about. There were internal forums for almost all kinds of topics. A few I remember fondly were a mathematics forum where colleagues would challenge each other with mathematical puzzles and a similar physics forum where, for some reason, crafting contrived paradoxes using special and general relativity and putting them up for debate was a common activity. The participants would analyse each paradox to determine if it truly was one or if it could be resolved into something that was no longer a paradox. I loved hanging out on those forums and made many friends there. The mathematics forum, in particular, gave me plenty of fun problems to think about. In fact, my Langford Pairing (2011) post was the result of a question I had stumbled upon there.

The human resources (HR) department used to organise afternoon games once every month where people would self-organise into teams and solve a small challenge. There was a cash prize for the winning team each time. The HR folks were very well aware of the nerd culture and the fascination with prime numbers, but they probably did not know enough about exactly what type of problems we were fascinated with. So in one of the monthly game events, the HR team gave us this challenge.

Write as many prime numbers between 1 and 1000 as you can in 5 minutes.

The 5-minute timer started immediately. Really, that was the challenge. We all looked at each other in surprise, wondering if that really was the problem. The game was already on. No constraints were set. Were we allowed to look up a list on the web? Probably not, otherwise what would be the point of the game?

There were five or six teams with a total of about 30 or so participants. We began working on the challenge. The first thing I did was load up the list of all 168 prime numbers from 1 to 1000 on my mobile phone and begin copying them meticulously to our sheet of paper.

I would learn later that another team had followed the same approach too. The person writing their list decided to omit a few numbers so that it did not look like they had copied the numbers verbatim from an external source. I think they were being overcautious because there were no rules, and all is fair in love and listing prime numbers.

I completed writing our list with about half a minute to spare. We turned in our sheets after the timer ran out. The HR folks then evaluated the sheets. The winner was announced. Our team won with all 168 numbers written accurately. We won the cash prize. One of the HR folks asked me later what formula we had used to generate all the prime numbers so accurately. I told them that we had used the ancient formula of looking up a list of prime numbers compiled by someone else and writing it down. We spent the cash prize immediately and ordered pizza and soft drinks for everyone.

The monthly afternoon games were not usually this silly. The other games were more interesting, more challenging and better designed. But I don't remember what those games were at all now. It is only this silly game that remains etched in my memory.