Have a look at the graph on the wikipedia page - should help you visualise it http://en.wikipedia.org/wiki/Logarithm http://en.wikipedia.org/wiki/Logarithm Yo

Have a look at the graph on the wikipedia page - should help you visualise it http://en.wikipedia.org/wiki/Logarithm http://en.wikipedia.org/wiki/Logarithm You want a curve, so that if the number of reps is higher, the suggested increase is proportional. Maths is easy. Let's go shopping!