Or just 2. I like my screen aspect ratios in decimal representation. The "wider" the image, the larger the number. Square would be 1.

It makes it easy to compare ratios: for example the aspect ratio of a movie (say 2.39) to my screen (2.33) and see that I can expect a good fit. My screen is a bit "more square", so there will be slivers of black borders on top and bottom.