Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site aecom.UUCP Path: utzoo!linus!decvax!mcnc!unc!ulysses!mhuxl!houxm!hogpc!houti!ariel!vax135!floyd!cmcl2!rocky2!cucard!aecom!poppers From: poppers@aecom.UUCP Newsgroups: net.math Subject: Re: Factorialize...or Fail! (spoiler - rot13) Message-ID: <466@aecom.UUCP> Date: Mon, 2-Apr-84 10:52:35 EST Article-I.D.: aecom.466 Posted: Mon Apr 2 10:52:35 1984 Date-Received: Thu, 5-Apr-84 01:24:17 EST References: <195@harvard.UUCP> Organization: Albert Einstein Coll. of Med., NY Lines: 15 Mr. Horton just posted the correct solution to the problem of 1! + 2! +...+ n! = k**2 in integers n and k. I thought that I might put the solution's logic another way: The sum of the first 4 factorials is 33, and since n! for n>4 is divisible by 10 (don't ask me why! Look up Nick's article!), higher sums will all have terminal digit 3. But all squares have terminal digit 0, 1, 4, 5, 6, or 9. ================== | PERITUS CLAVIS | Michael Poppers | MACHINAE VIVIT | ** poppers @ aecom ** ================== >