The 2-Minute Rule for Numbers
N ⊂ Z ⊂ Q ⊂ R ⊂ C ⊂ H ⊂ O ⊂ S ⊂ T ⊂ ⋯ displaystyle mathbb N subset mathbb Z subset mathbb Q subset mathbb R subset mathbb C subset mathbb H subset mathbb O subset mathbb S subset mathbb T subset cdots Real numbers are least upper bounds of sets of rational numbers which are bounded higher than, or greatest decrease bounds of set