As, we observe the pattern Inside number Inside number = (difference)(difference)! =( Greater number - Smaller number ) (Greater number - Smaller number)!
i.e. 1=(2−1)(2−1)!,424=(12−8)(12−8)!, 36=(7−4)(7−4)! ∴?=(5−3)(5−3)! ∴ Required number =22!=22×1=4