TITLE: Why do mathematicians use this symbol $\mathbb R$ to represent the real numbers?
QUESTION [8 upvotes]: So, I'm wondering why mathematicians use the symbols like $\mathbb R$, $\mathbb Z$, etc... to represent the real and integers number for instance. I thought that's because these sets are a kind of special ones. The problem is I've already seen letters like $\mathbb K$ to represent a field in some books just to say an example. So, someone knows why we use these kind of symbols?
Thanks

REPLY [2 votes]: See the section "Letters for the sets of rational and real numbers" at http://jeff560.tripod.com/nth.html