Flowers (like this sunflower) often have seeds arranged in Fibonacci numbers of spirals running in each direction Stuart Monk/Alamy
Converting between units is often something you have to do on the fly, and it is made easier when you memorise some rough equivalents. For instance, an imperial pint is 568 millilitres, but I often think of it as being about half a litre to make conversions simpler. I know a yard is a bit less than a metre, there are 2.2 pounds in a kilogram and a foot is 30 centimetres (thanks to rulers).
But maths gives us a…
