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"If we find a prime $p$ such that $p\mid n$ , then $n/p$ is a positive integer that's smaller than $n$."

I understand $n/p$ is $n$ divided by $p$ but what is $n\mid p$?

blue-sky
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    ... why the downvotes? – Dustan Levenstein Jul 20 '16 at 19:15
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    @DustanLevenstein Probably because even the most cursory of Google searches would answer OP's question (and this has been asked previously). – Daniel W. Farlow Jul 20 '16 at 19:17
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    To be fair to the OP, it is difficult to search for that vertical bar in a "cursory" (I had to look that word up) search. And if you search for "math symbol |" you end up at a big page of math symbols that has over 40+ occurrences of that symbol. Yes the answer is easy to find via Google but not with a "cursory" (I love that new word!) search. Gotta think a little to search for symbols. – Ray Toal Jul 20 '16 at 22:11
  • @RayToal I definitely agree! The first time I saw the | symbol, I looked through that page you speak of to connect a bunch of dots. This question is definitely useful. – Jeel Shah Jul 20 '16 at 22:12
  • @DanielW.Farlow If that really is the best explanation you can come up with, then I'm going to have to join a few other people and give this question a compensatory upvote. Sorry, but I agree with Ray. This is not easy to Google. – Dustan Levenstein Jul 20 '16 at 23:57
  • @DustanLevenstein I guess the real issue at heart here, then, is how to effectively Google. My quick search of vertical bar math notation gave me exactly what I needed, the first page (Wiki) being somewhat more difficult to find the needed information but the second result being exactly what is needed. Regardless, many people cannot Google effectively, and that seems to be the issue more than anything. Oddly, I think the context here, more than anything, should have pointed OP in the right direction. – Daniel W. Farlow Jul 21 '16 at 00:52
  • @DanielW.Farlow That's not really the issue here. The issue is that 3 people thought it was appropriate to silently downvote the question instead of providing the OP with any useful feedback. I just do what I can to raise people's attention to the problem of inappropriate downvotes. – Dustan Levenstein Jul 21 '16 at 02:03
  • @DustanLevenstein Downvote: This question does not show any research effort; it is unclear or not useful. As far as I'm concerned, the question showed no research effort, and I should not feel like I have to justify every single downvote I give (I find it rather priggish of you to judge anyone's "silent downvote" as inappropriate). Have you left 57 comments for the downvotes you have given? The question concerning downvotes has been beaten to death on meta, and it is not a fruitful discussion to have. I suppose we shall simply have to agree to disagree here. – Daniel W. Farlow Jul 21 '16 at 02:08
  • @DanielW.Farlow I try to make sure there is clear justification for every downvote I give (though I'm not always the one who gave it). I wouldn't be surprised if you could find an exception among those 57 downvotes (quite a small number, considering how long I've been on this website), but I'm human. Generally, I don't think a silent downvote is appropriate on this website. Period. Close votes provide feedback. Comments provide feedback. Silent downvotes do not. – Dustan Levenstein Jul 21 '16 at 02:12

3 Answers3

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For nonzero integers $x$ and $y$, the following are equivalent statements:

  • $x$ divides $y$

  • $x\mid y~~~~~~~~~~~~$(this is read aloud the same way as the previous line)

  • $y$ is divisible by $x$

  • $y\equiv 0\pmod{x}$

  • $\frac{y}{x}$ is an integer

  • There exists some integer $k$ for which $xk = y$

  • $y$ is a multiple of $x$

  • $x$ is a factor of $y$

On the other hand, $x/y$ is in this context another way of writing the fraction $\frac{x}{y}$

JMoravitz
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    "$y/x$ is an integer" is only equivalent if $x \ne 0$ (unless for some reason you want to throw out the case $0\mid 0$). –  Jul 20 '16 at 19:24
5

The expression "$n/p$" represents the number that you get when you divide $n$ by $p$, whereas the expression "$p\mid n$" represents the statement that $p$ divides evenly into $n$.

4

$p \mid n$ means "p divides n" or $\exists k\in\mathbb{Z}$ so $n=pk$

n1000
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