Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: nyu notesfiles V1.1 4/1/84; site acf4.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxj!houxm!vax135!cornell!uw-beaver!tektronix!hplabs!hao!seismo!cmcl2!acf4!leung From: leung@acf4.UUCP Newsgroups: net.puzzle Subject: Series sol'n/con't Message-ID: <21700001@acf4.UUCP> Date: Sat, 22-Sep-84 16:18:00 EDT Article-I.D.: acf4.21700001 Posted: Sat Sep 22 16:18:00 1984 Date-Received: Wed, 26-Sep-84 04:35:50 EDT Organization: New York University Lines: 34 Nf-ID: #N:acf4:21700001:000:958 Nf-From: acf4!leung Sep 22 16:18:00 1984 >>What is the next number in the following series (and WHY)? >>2 3 10 12 13 20 21 >>Thanks in advance for your erudite responses! >>-- >> Tom Butler >> ..!ihnp4!ihuxn!ttb ok, the answer is : 2 3 10 12 13 20 21 *22* *30* *31* *32* *40* WHY: Well, lets look at the progression of 2,3,10,12,13,20 You can see that the ones digit in each number goes as follows 2,3,0 when the progression is changed after 20 by the number 21 by subtracting 1 (one) from the ones digit for non-zero numbers the progression is changed to: 1,2,0 The zero digit cannot be changed as that would royally mess things up (in my opinion). Of course the whole progression could change so that the following results: 2,3,10,12,13,20,21,22,29...[now you tell me what the next number in the sequence is!] Alex Polozoff New York University