--- Jean-SC)bastien Bour <[EMAIL PROTECTED]> wrote: > Reid Nichol a icrit : > > --- Jean-So?=bastien Bour <[EMAIL PROTECTED]> wrote: > > > >> Matthias Kilian a icrit : > >> > >>> a) 4 is the first non-prime, at least according to factor(6). > >>> > >>> > >> No, it is 1 :) > >> Explanation : a prime number can only be divided by two different > >> numbers : 1 and itself. 1 can only be divided by one number, > >> therefore it is not prime. > >> > > > > Wrong. > > > > You got the definition of what a prime number is wrong. A prime > > number is defined as a positive integer greater than one which has > > positive divisors 1 and itself, only. > > > > Please note that using your definition 7 is not prime because -7, > > -1, 1 and 7 all divide 7. > > > > I suggest at least looking into elementary number theory before > > making such statements again. > > > > > No no not wrong, indeed I didn't talk about being positive. But being > prime is being positive (should have said it I agree) and have EXACTLY > TWO different divisors. And if 1 were prime you wouldn't have only > one unique decomposition in prime numbers ;) (for exemple, is 45 = > 3x3x5 or 1x3x3x5 or 1x1x1x3x3x5 or... ?) It would crush many things > down about arithmetics. > > Luckily I have learnt some things during my two year special > scientific studies (heard about "Classes priparatoires" in France ?) > and this is one of those. > >
Point of fact, your definition did /not/ state that a prime number had to be positive. Point of fact, your definition did /not/ state that the divisors must be positive as well. Perhaps you should've spent more time listening in class. Or even just listening to me. Or look it up at mathworld, or wikipedia. They all prove that your definition is *wrong*. Perhaps those classes that you supposedly took should teach something about mathematics aside from just using them. best regards, Reid Nichol "We're in a giant car heading into a brick wall at 100 miles/hr and everybody's arguing about where they want to sit." -David Suzuki Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com
