The 1954 Statelessness Status Convention provided a definition of a stateless person (which has since become part of customary international law, according to the International Law Commission), and sets out a number of rights that stateless persons should enjoy.
The ratio of two integers P and Q can be expressed as P : Q or P/Q. In both cases, you may divided P and Q by their greatest common factor so as to express the ratio in its simplest form.
The factorial of a number is represented by the exclamation point (!). The factorial of a number $x$ is often described as the product of all positive integers less then or equal to $x$. For example: $$4! = 4\cdot3\cdot2\cdot1 = 24$$.