There you are happily wandering through the pre-Christmas melee when, out of the blue, something of a revelation hits you right between the primes.
We, my nine year old twins and I, had spent the day chasing Christmas trees, writing cards, sorting out the lights and all those other festive bits and pieces. Lacking energy, I caved (well it didn't take much to be honest) and agreed to chips for tea. Added the compulsory greenery and we sat down to tea with the usual demand for a quiz (sometimes its our version of Twenty Questions...). Anyway Megan's chosen subject: Maths.
Mum invents the questions and to get to the point, a discussion ensued on how to identify whether or not a number is prime. Caitlin asks: "Is three billion and 1 a prime number?" I can't answer in the time available (Strictly Come Dancing is going to start soon). Then Caitlin announces that, apparently, all prime numbers are either one less than, or one more than a multiple of six. Therefore, it seems, that you can at least say that a number is not prime if that requirement is not met.
They all rushed off to watch the semi final - the maths of the SCD quarter and semi finals is another story - leaving me to discover that this multiple of six thing is true and to wonder why I had never heard that before. Maybe it's just me that it has passed by or that has passed it by...
Nine year olds...hah!
Views, opinions, impressions and statements are the personal expressions of Marten Gallagher, ATM Web Editor
and are not necessarily those of the Association of Teachers of Mathematics
