trifecta betting calculator|trifecta wheel cost chart : Pilipinas The formula for calculating any trifecta bet is: Trifecta combinations = (A x B x C) – (AB x C) – (AC x B) – (BC x A) + (2 x ABC) Where: A = Number of selections for 1st place; B = Number of selections for 2nd place; C = Number of selections for 3rd place; AB = Number of selections for 1st and 2nd place; AC = Number of selections for 1st .