This document is, who are considered to try to learn about information, for those who are currently learning the data representation and computation of the internal computer that is a basic knowledge of computers in high schools and universities of the information system, so that with the help of understanding guide you through putting carefully intermediate calculation formula. In addition, not only the base conversion radix, has recently been important, capacity calculation of the magnetic disk required for big data processing, including the access time calculation, important IP address calculation in the network, such as the processing speed of the computer also put you have. Example, will help to immediately practice because it is exercise format. More specifically, basic information technician test of the national examination, information technology proficiency test, put out the first example until the application issues from the basic problem of the information that will appear on the exam in the employment test, also be used, such as drawing the commentary It has been carefully commentary to. Next, questions the Ruidai as a problem, can now be sure that you understand. Answer commentary has put in detail to the middle of the formula at the end of the chapter.