Letter: It's a wrap

From Jeremy Hawkes

Mathematician Ian Stewart’s thoughts on wrapping mince pies in string (20/27 December 2008, p 67) looked like a simple way to encourage an interest in maths in my 9-year-old son. We put string around 6 AA batteries – even more plentiful than mince pies at our Christmas – and found that 20 centimetres of string fits around the circles in a sausage configuration, and 13.5 cm fits around either a triangle or two parallel rows.

Now how do I explain that mathematics is not always the best tool to use?

From Richard James

I am struck by an odd coincidence: for wrapping spheres the sausage arrangement is best up to 56 spheres and then 57 or more are best wrapped as a cluster. But 56 is also the atomic number of iron, which I gather is the heaviest element whose creation by fusion releases energy.

I can’t help wondering whether there is some connection between these two facts.

Otterbourne, Hampshire, UK

Liverpool, UK