Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

$A = \{1,2,3,4,5\}, B = \{1,2,3,4,5,6,7,8\}$

$A - B =$ ?

Does that just leave me with $\emptyset$? Or do I do something with the leftover $6,7,8$?

share|cite|improve this question
Yes, it is empty. Not that it's $\emptyset$, and not $\{\emptyset\}$ here. – 1015 Feb 7 '13 at 16:45
Fantastic, thanks! – KKendall Feb 7 '13 at 16:48
up vote 4 down vote accepted

$A - B = \emptyset$, because by definition, $A - B$ is everything that is in $A$ but not in $B$.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.