Six and counting... maths, Rishi Sunak, and fairy tales (Anne Rooney)

A prime number of dwarfs, Arthur Rackham

 This week, the British PM suggested the poor numeracy skills of Britain's school leavers could be improved by forcing them to learn maths up to 18 years of age. (Of course, the obvious answer is that their poor numeracy skills could be improved by teaching them maths properly to start with, but never mind that for now.) And today I heard from an American friend and college professor that her students (doing humanities degrees) don't know any fairy tales except any they have seen as Disney movies. That is, 59 out of 60 don't and the 60th is German. So I thought I'd put these two together, because if you don't know any maths, you can't understand fairy stories anyway, because numbers are really important in fairy stories.

There are three bears. There are seven brothers/dwarves etc. There are never seven princesses (someone correct me if I'm wrong).* There are two sisters if they have equal parts to play (Rose Red and Snow White are essentially one). Dancing princesses come by the dozen. But bad step-relatives come in threes (mother and two sisters). Genies give you three wishes. You usually get three tries at something before it all goes to pot — three nights to spin straw into gold, three chances at blowing down a house full of pigs, three chances at frog-kissing, three chances at abandoning your kids in the wood. There are seven corpses in Bluebeard's cold room. What do we notice? Prime numbers if you're male or bad. Even numbers if you're female and good. You can predict that Bluebeard's eighth wife won't die because he already has seven dead wives and no baddie can end up with an even number of dead wives. (I know, there must have been a time when he had four or six, but the story wasn't ending then.) You know the bad fairy is going to turn up in Sleeping Beauty because there are never 11 fairies. And you know she will be defeated in the end because there must be a twelfth wish and as it's an even number it's going to triumph.

I know people have related number in fairy tales to religion and other things, but that's just pushing the issue backwards. It's no use to say there are 12 dancing princesses/disciples and think that's an answer, because why are there 12 disciples? Probably for the same reason there are 12 hours of daylight — 12 is a useful number as it's the first number you get to that has more than two factors (2x6, 3x4). And 3 and 7 go the other way becaus they're prime; you can't do anything with them. You can't pair off the dwarfs, or Billy Goats, or bears - they each need a distinguishing feature.

Of course, thinking about numbers in fairy stories won't help you work out compound interest or calculate your tax. Though... if Goldilocks takes one spoon of porridge from each bowl, is she using the same spoon for each or a spoon of corresponding size? If the first, she takes the same volume from each of the first two bowls but a larger percentage from the middle bowl. If the second, she takes the same percentage but a smaller amount from the middle bowl... Given that her mass is too great for Baby Bear's chair, but not his bed, we can conclude that his parents made/bought a bed he could grow into. How much money did the bears save by cutting down the number of beds they will have to buy over his cubhood? See, we can kill two birds with one stone here. (The two birds are, essentially, a single killing as they don't need to be individually distinguished).

*I am not claiming this is thorough or scholarly. It's an idle muse, riffing on apparently entirely separate stories, because I like seeing what can come out of juxtapositions.

Anne Rooney

Out now: Baby Polar Bear, Oxford University Press