NetRexx arithmetic attempts to carry out the usual operations (including addition, subtraction, multiplication, and division) in as “natural” a way as possible. What this really means is that the rules followed are those that are conventionally taught in schools and colleges. However, it was found that unfortunately the rules used vary considerably (indeed much more than generally appreciated) from person to person and from application to application and in ways that are not always predictable. The NetRexx arithmetic described here is therefore a compromise which (although not the simplest) should provide acceptable results in most applications.