<p>5 has the factors 5, 1, and -5. Is this true that negative numbers are also factors of their positive multiples? </p>
<p>edit: actually it has 4.</p>
<p>5,1,-1,-5.</p>
<p>-5*-1=5</p>
<p>I don't much like the definition of factors (because they don't include fractions), but yes, negatives -do- count as factors. They, however, are commonly left out. After all, it's the same as positive, just negated.</p>
<p>Also, as a side note, 0 has an infinite number of factors</p>
<p>According to the SAT, they are NOT counted. I just did a test (test number 6 I believe) that asked a question about how many factors were in a certain number, and negatives were NOT included in the correct answer.</p>
<p>EDIT: Of course, that "test" I did above was from the blue book.</p>
<p>Negative numbers <em>DO NOT</em> count as factors. The number 5 has two factors.</p>
<p>im_blue is correct</p>
<p>Not positive about this, but factors are ONLY positive while divisors can be positive and negative.</p>
<p>I think it is only two factors becuase it results from the prime factorization of numbers.</p>
<p>Look here: <a href="http://mathforum.org/library/drmath/view/63516.html%5B/url%5D">http://mathforum.org/library/drmath/view/63516.html</a></p>