Aser Abdelfatah Attia

Official IYMC Ambassador

Aser Abdelfatah Attia
Egypt, New Cairo
Stem High School For Boys - 6th October

I conceptualize Mathematics in problem-solving, which I think is the purest manifestation of the rhythm of breakage and building. This rhythm always follows; however, Mathematics took this rhythm to the next level with the beauty of Recursion. I remember how the blessing of recursion manifested in the solution of the problem “find the last 2 non-zero digits of 2017!.” “Why don't you try and solve it?” I told myself. I thought the brute force algorithm would work, but I got stuck at 11!, and my calculator couldn’t reach 80! All I had was the equation 2017! mod 10^(number of last zero digits +2) = X. After I examined the first few factorials, I found a recursive equation for the number of the last zero digits. The equation advanced to 2017! mod 10^504, which, however, seemed further unapproachable, but at this point, the complexity starts collapsing, and the solution’s simplicity started to emerge. After a little more analysis, it was apparent that 2017! is equal to a recurring formula: (5n+1)*(5n+2)*(5n+3)*(5n+4)*2016*2017 mod 100 where n = [1, 403]. The solution continued to disassemble what seemed to be a tortuous maze until it became just a puzzle (not the Five room puzzle of course {^_^}).

Contact: aseattia(at)amb.iymc.info View Full Team