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Wednesday, 29 June 2011

Favourite numbers, and other nonsense

Alex Bellos is asking people for their favourite numbers. This is an international survey in which people are asked whether they have a favourite number or not and, if they do, the reasons for their choice, plus, optionally, a few minor demographic details. Alex is getting some press for this, with recent appearances on the Today programme and other radio programmes.

On the Math/Maths Podcast recently, Samuel Hansen and I had a chat with James Grime and Samuel spoke with Alex Bellos about favourite numbers. These items caused Christian Perfect to get in touch and he joined us on the most recent episode to give, in his words, a robust defence of having a favourite number. At the recent Maths in the City awards event Christian had asked Marcus du Sautoy what his favourite number was and he said he didn't have one until the press kept asking him for his. This led us into a discussion about the media. I find it irritating that a radio presenter has a mathematician on their show and feels "what is your favourite number?" is an appropriate question. I regard it as silly. Christian said he didn't think it was a silly question because people have favourite all-sorts-of-things. Samuel said, while it was a silly question, he felt it was a decent opening question from someone who didn't understand mathematics. What do you think? I hope you will give your view in the comments below this post.

Part of what I worry about is the proximity of this sort of question to asking mathematicians on the spot questions like, "what is 33 squared?" I feel this has very little to do with mathematics and should be discouraged. Recently I took a puzzles stall to a local science fair and someone commented that one of the puzzles was "proper maths" because it involved numbers. I said I had specifically avoided puzzles that involved arithmetic because there's so much more to mathematics than that.

Next, I saw Christian was speaking on Twitter with Edmund Harriss about a recent blog post Edmund had written on imparting meaning to numbers. In this, Edmund gives a defence of numerology, writing of it as a game which allows space for creativity, one that may mean you accidentally stumble on something meaningful. (Go and read what Edmund says. I'll wait.) I don't disagree with what Edmund says but positive effects and harmless fun aren't my problem with numerology.

I probably don't need to say on a mathematical blog but I don't believe in numerology. This is the process of extracting a number from some context, through some seemingly arbitrary calculation, and then assigning meaning to that number in an attempt to understand the context or make a prediction (perhaps from some cosmic ordering of the universe). I'm tempted to feel that while it is having a positive effect and sometimes even encouraging people to feel better about their lives it's probably tolerable. It isn't hurting anyone. Often, though, the negative consequences seem like to lead to unhappiness or financial loss. Your name derives a particular number? Well then you're in for a cruel fate, or are destined to be a terrible person. Not that you can help what you are called (advice I have read for making these 'calculations' has it that it is only the name on your birth certificate that counts). If you made this calculation and took seriously that you were destined to be denied happiness, prone to addiction or compelled to violence, I can only imagine what this must do to a person. There are other such negative effects. The stock market closed at a value with particular digits? A huge crash must be coming and you should sell your shares immediately, no matter the loss. This is your birth date? Then your true sole mate will have this birth date, and since this isn't the birthday of your current girlfriend, you'd better leave her. (You're happy being with her? Well that isn't really the point.)

Another aspect, I worry, is the possibility of engagement with this sort of thinking contributing to others sorts of poor numerical thinking skills. If numbers have this mystical property, people may find them mystifying. "Three times as likely", you say? That's very likely then! "95% certain to happen", there's no way that won't happen; but a 1 in 20 chance of winning, wow, that could be me! And so on. I worry that being loose with the meaning assigned to numbers in different contexts, even in a meaningless and harmless way, may lead to being loose with numbers in other, more damaging contexts. As Edmund points out, we should play with numbers and not be afraid of them but if we assign meaning to a numerical measure we must remember that meaning when playing and take care when comparing numbers from different contexts.

So, do I think Alex's experiment is silly and should be avoided? Well, no. I think his is an interesting experiment precisely for the reasons he is carrying it out. Not to determine if there is some great cosmic significance in numerical ordering, but as a sociological experiment to investigate the cultural effects of our relationship with meaningless numbers. So go, now, and fill out the survey. It genuinely will only take a minute and you are contributing to an interesting experiment.

Please share your thoughts about this post by clicking on the comments option below.
Peter Rowlett blogs at Travels in a Mathematical World.


  1. Assuming you've already talked about whatever book you're promoting or campaign you're the figurehead of or whatever other reason it is that a mathematician needs to be interviewed for, if the interviewer still has some column inches to fill they're probably going to have to ask some pretty inane questions. I think that applies to anybody being interviewed, not just mathematicians.
    So what would a non-silly general interest interview question for a mathematician be? I'm having trouble thinking of one, but if someone does come up with one maybe we could pass it around to journalists for future use.

  2. A couple of minutes' googling has turned up this interview with Bernd Sturmfels. I think anything along the lines of the questions on the first page would be a good replacement for "What's your favourite number?"

  3. I do not think that asking a person for her or his favourite number is a silly question. It would be silly to give any significant meaning to the answer.

    I filled out Alex Bellos survey without a moments hesitation. I do have a favourite number and the reason is induction.
    My favourite number, 37, always got used in examples by my professor. When I asked my professor why he always used 37, he answered: "My professor always used 37 in examples."

  4. Goofy, but 88 is my favorite number. It's symmetrical in so many ways (even, vertical and horizontal, doubly infinite) and I love writing eights.

  5. 157. It's just super pretty and comforting.

  6. I guess it's ok to have a favourite number if you like, but a mathematician talking to the press should be ready with an answer like "zeta(3)", say, and when the interview asks "what's that?" the mathematician has an opportunity to explain a little of the history/complexity/people/etc. in maths (though I guess he'd have to talk quickly before the interviewers eyes glazed over - Peter would do well at this!).

  7. 42!

    I have loved Douglas Adam's work since I was first introduced to it by my brother.

    The idea that a single number contains the answer to all the big questions in the universe is just so wonderfully wacky, I find it hilarious.

    (And the question of course, is "How many roads must a man walk down?")

  8. It's time mathematicians reclaimed the term "numerology" for "the study of numbers" which is its literal root meaning. The correct term for use of numbers in fortune telling is "numeromancy".

  9. Call me a smartypants but my favourite number is Feigenbaum's (first) constant, purely because of it unexpectedness. To show I'm not a completely up-to-date mathematician, I admit that I didn't know he had a second constant till I first responded to this question a year ago.