This is a 12 page document that explains each of the categories in the real number system (natural numbers, whole numbers, integers, rational numbers, irrational numbers).
This would make an excellent "cheat sheet" or study guide for a test. (I also have a real numbers test for sale so see my store). Included are the pages with the information written out and the exact same pages with blanks in certain areas so the students can fill in for note taking.
This is included in my Real Numbers bundle here: