Ereygan wuxuu leeyahay 3 Qaab iyo macneyaal kala duwan.
abnaq1
Magac lab
Xisaab
Tirada soo baxda marka la isku dhufto dhammaan abyooneyaasha togan ee ka yar ama le'eq abyoone togan ee la isa siiyey. Abnaqa abyoone n oo loo qoro n! waa: (n - 1) (n - 2) (n - 3) ... 3. 2. 1. Cidala isku raacay o! = 1.