On Wed, 20 Nov 2013 00:54:28 -0500, Dave Angel wrote: > On 20 Nov 2013 03:52:10 GMT, Steven D'Aprano <st...@pearwood.info> > 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"
This ambiguity is a great example of why teachers (and enayone else responsible for specifying a programming project) should take greater care when specifying tasks. if it is to late to ask for clarification (the correct step in a real world case) I suggest you write 2 programs 1 for each interpretation, it will be good for your personal learning even if the teacher does not give any extra credit. -- I am practicing a fine point of ethics. It is acceptable to shoot back. It is not acceptable to shoot first. -- Zed Pobre -- https://mail.python.org/mailman/listinfo/python-list