Path: csiph.com!usenet.pasdenom.info!news.albasani.net!feeder.erje.net!eu.feeder.erje.net!ecngs!feeder2.ecngs.de!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.012 X-Spam-Evidence: '*H*': 0.98; '*S*': 0.00; 'english.': 0.04; 'true,': 0.05; 'test,': 0.07; 'integers': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:Help': 0.11; '120,': 0.16; '5),': 0.16; '60,': 0.16; 'precedence': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'applies': 0.16; 'wrote:': 0.18; 'trying': 0.19; 'header:User-Agent:1': 0.23; 'question': 0.24; 'gets': 0.27; 'header:X-Complaints-To:1': 0.27; 'header:In- Reply-To:1': 0.27; "doesn't": 0.30; '13,': 0.31; 'apparently': 0.31; "d'aprano": 0.31; 'steven': 0.31; '(i.e.': 0.33; "i'd": 0.34; 'test': 0.35; 'next': 0.36; 'should': 0.36; 'positive': 0.37; 'two': 0.37; 'nov': 0.38; 'to:addr:python-list': 0.38; 'does': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'how': 0.40; 'course.': 0.60; 'numbers': 0.61; 'first': 0.61; 'series': 0.66; 'believe': 0.68; 'therefore': 0.72; '"not': 0.84; '49.': 0.84; 'states,': 0.91; 'subject:Friend': 0.91; 'remember,': 0.93; '2013': 0.98 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Dave Angel Subject: Re: Newbie - Trying to Help a Friend Date: Wed, 20 Nov 2013 00:54:28 -0500 References: <0e127888-4bfa-4f14-aa55-df8ef53284a3@googlegroups.com> <528bff92$0$29992$c3e8da3$5496439d@news.astraweb.com> <528c31e9$0$11089$c3e8da3@news.astraweb.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Gmane-NNTP-Posting-Host: 174.32.174.29 In-Reply-To: <528c31e9$0$11089$c3e8da3@news.astraweb.com> User-Agent: Groundhog Newsreader for Android X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 34 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1384926852 news.xs4all.nl 15925 [2001:888:2000:d::a6]:42486 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:60054 On 20 Nov 2013 03:52:10 GMT, Steven D'Aprano wrote: > 2 does count because it isn't divisible by 3. The question states, > "[count] how many positive integers less than N are not divisible by 2,3 > or 5". Two is not divisible by 3, so "not divisible by 2,3 or 5" is true, > so two gets counted. > The first number which is divisible by *all* of 2, 3 and 5 (i.e. fails > the test, and therefore doesn't get counted) is 30. The next few that > fail the test are 60, 90, 120, 150, 180, 210, 240, 270, 300, ... > Remember, these are the numbers which should not be counted. > > I count 1, not 6 > Out of curiosity, which number did you count? 1 of course. It's the only one that's not divisible by any of the factors. Apparently we disagree about precedence and associativity in English. I believe the not applies to the result of (divisible by 2, 3, or 5), so I'd count 1, 7, 11, 13, 17, 19, 23. The first nonprime would be 49. If I were trying to get the series you describe, I'd phrase it as "Not divisible by 2, and not divisible by 3, and not divisible by 5" -- DaveA