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.
Let's say you are multiplying two numbers, just two two-digit numbers for now (though the rules could be adapted for others) which start with the same digit and the sum of their unit digits is 10. For example, 87Ã83 (sum of unit digits: 7+3=10). You multiply the first digit by one more than itself (8Ã9 = 72). Then multiply the second digits together (7Ã3 = 21). Then stick the first answer at the start of the second to get the answer (7221).