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machines; that; for; in; example; error; either; times; which; electronic; mechanical; or; through; than; human A computer is a machine designed to perform work mathematically and to store and select information that has been fed into it. It is run by [51] mechanical or electronic means. These [52] can do a great deal of complicated work [53] a very short time. A large computer, for [54] , can add or subtract nine times a second, multiply a thousand [55] a second, or divide five hundred times a second. Its percentage of [56] is about one in a billion digits. It has been estimated [57] human beings making calculations average about one mistake per two hundred digits. The heart of an [58] computer lies in its vacuum tubes, [59] transistors. Its electronic circuits work a thousand times faster [60] the nerve cell in the human brain. A problem that might take a human being two years to solve can be solved by a computer in one minute, but in order to work properly, a computer must be given instructions--it must be programmed.