calculandum

UK /ˌkalkjʊˈlandəm/

Etymology A substantivisation in English of the Latin calculandum (the nominative neuter singular form of calculandus, “which is to be calculated”, “which is to be computed”, the future passive participle (gerundive) of calculō, “I calculate”, “I compute”), on the pattern of analysandum, cogitandum, explicandum, memorandum, etc.