We analyse abstract data types that model numerical structures with a concept of error. Specifically, we focus on arithmetic data types that contain an error flag ⊥ whose main purpose is to always return a value for division. To rings and fields we add a division operator x/y and study a class of algebras called \textit{common meadows} wherein x/0=⊥. The set of equations true in all common meadows is named the \textit{fracterm calculus of common meadows}. We give a finite equational axiomatisation of the fracterm calculus of common meadows and prove that it is complete and that the fracterm calculus is decidable.