premise: For those who are unfamiliar with computers and the need for a word-processing package, I should explain that when you buy what is fondly call a  personal  computer, you get three pieces of equipment (though they may be combined in some models or makes): a rectangular box with some slots in the front and sockets in the back, a monitor, which is nothing but a small TV set, and a keyboard, which looks like an ordinary typewriter keyboard but, in many models sold today, has a number of additional keys alongside those for the familiar alphanumeric  on mine, nestled among some control keys on the right side is what is called a  number pad,  which resembles the key arrangement one sees on a small adding machine or calculator; on the left side is a double bank of five keys marked  F1  through  F10  which, when pressed alone or in combination with another key, perform certain functions, some of which are useful, others of which are evidently thought useful by the manufacturer but which I never use.
hypothesis: Computers are usually sold with keyboards.