(3!)! = 6! = 720
(8! - 7! + 6!) × 4!/6! = (8 × 7 × 6! - 7 × 6! + 6!) × 4!/6!
= (56 × 6! - 7 × 6! + 6!) × 4!/6!
= (56 - 7 + 1) × 6! × 4!/6!
= 50 × 6! × 4!/6! = 50 × 4! = 50 × 24 = 1200
