>[!abstract] >A mnemonic for the nesting of number sets, from most nested to least: > >$\mathbb{N}$ for natural numbers (positive integers); >$\mathbb{Z}$ for all integers, positive and negative (Z stands for *Zahl* or integer in German); >$\mathbb{Q}$ for rational numbers (i.e., those that can be expressed as a ratio; Q stands for quotient); >$\mathbb{R}$ for real numbers; >$\mathbb{C}$ for complex numbers (i.e., those with an imaginary part).