| [ QuizWit ] in KIDS 글 쓴 이(By): guest (wiking) 날 짜 (Date): 1998년01월07일(수) 03시32분15초 ROK 제 목(Title): Re: [문제] n! From the number of 0's: 40<= n <= 44. Now let's do consider the last non-zero digit. Define L(a) = the last non-zero digit of a. Using L(10!) = 8, L(20!) = L(8*8*3*2) = 4 L(30!) = L(4*8*5*3) = 8 L(40!) = L(8*8*7*4) = 2 L(41!) = L(2*1) = 2 L(42!) = L(2*2) = 4 L(43!) = 2 L(44!) = 8 Hence n = 42. |