Kalmar “denumerable” sifa ce da ke bayyana saiti ko tarin da za a iya ƙidaya ko ƙidaya. A cikin sharuddan lissafi, saiti mai ƙididdigewa saitin ne wanda za'a iya sanya shi cikin wasiƙa ɗaya zuwa ɗaya tare da saitin lambobi na halitta (watau lambobi 1, 2, 3, ...). Wannan yana nufin cewa kowane kashi a cikin saitin za a iya sanya masa lamba ta musamman, kuma akasin haka. (misali, 2 an haɗa shi da 1, an haɗa 4 tare da 2, an haɗa 6 da 3, da sauransu). A gefe guda kuma, saitin duk ainihin lambobi ba ƙididdigewa ba ne saboda ba za a iya sanya shi cikin wasiƙa ɗaya zuwa ɗaya tare da saitin lambobi na halitta ba (tabbacin wannan gaskiyar an ba da hujja ta Cantor's diagonal muhawara).