** Introduction**

An understanding of renal and dialysis medicine depends greatly upon an ability to understand units of measurement, particularly as applied to solute concentration, and to undertake calculations using both small fractions and very large numbers. We also need to understand some of the mathematical tricks that are used to transform less manageable numbers to a manageable form. The behavior of solutes, as their concentration in blood or other body fluid, is critical to the understanding and the measurement of disease and of therapeutic intervention. Interesting phenomena are rarely random but nor do they always conveniently behave in a predictable and linear fashion. There are mathematical means of describing such relationships and, in some cases, we require some competence in the mathematics themselves.

This article is not a math primer, but points to a few areas where we require some familiarity with mathematics over and above that which gets us through the weekend shopping.