This paper presents a historical review of selected material covering the development of quantitative methods and tools involved in management decision-making. Although the science of the computer has evolved recently, the principles behind them can be traced over many years in the past. Men such as Taylor and Fayol not only developed quantitative techniques but also wrote most of the material which describes the results of their experiments. They believed that sciences such as engineering should have some basis in management and did much to encourage the teaching of management in the engineering schools. In some areas managers did not develop the tools but were instrumental in the application of the techniques. This paper traces these tools from the development of the abacus around the year 1100 B.C., followed by an enumeration and explanation of various operations research tools, methods and models.