How do you express the Ratio of two integers?

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. Alternatively, you may multiply both by some number so that the first part is 1 or the second part is 1 (both unit ratiOS), or the second part is 100 (a percentage), or a million (part per million) and so on.