(jeden) Jakub; (bez) Jakuba; (k) Jakubovi; (vidím) Jakuba; (hej) Jakub!; (o) Jakubovi; (s) Jakubom;
(štyria) Jakubovia; (bez) Jakubov; (k) Jakubom; (vidím) Jakubov; (hej) Jakubovia!; (o) Jakuboch; (s) Jakubmi;