Number entry systems on medical devices are safety critical and it is important to get them right. Interaction design teams can be multidisciplinary, and in this work we present a process where the requirements of the system are drawn up using a Controlled Natural Language (CNL) that is understandable by non-technical experts or clients. These CNL requirements can also be directly used by the Quality Assurance (QA) team to test the system and monitor whether or not the system runs as it should once deployed. Since commonly, systems are too complex to test all possible execution paths before deployment, monitoring the system at runtime is useful in order to check that the system is running correctly. If at runtime, it is discovered that an anomaly is detected, the relevant personnel is notified through a report in natural language.