小数在计算机内有两种表现形式定点数和浮点数。在定点机中，由于小数点的位置固定不变，以此当机器处理的数不是纯小数或纯整数的时候，必须乘上一个比例因子，否则会产生“溢出”。而实际上计算机处理的数不一定是纯小数或纯整数，而且有些数据的数值范围相差很大，不能直接用定点小数或定点整数表示，必须用浮点数来表示。浮点数的表示精度要比定点数高的多。要求用定点运算来仿真浮点运算，用定点数运算的思想去实现浮点数的运算。-Decimals in the computer, there are two manifestations of fixed-point and floating-point numbers. In the fixed-point machine, because of the location of the decimal point is fixed, as when dealing with a number of machines is not pure decimal or pure integer, the ratio must be multiplied by a factor, otherwise will have a　spillover.　In fact a number of computer processing is not necessarily the pure decimal or pure integer, and some of the numerical range of data varied widely, not directly with fixed-point or fixed-point decimal integer that must be expressed in floating-point numbers. Floating-point precision than that of fixed-point higher. Asked to use fixed-point calculations to simulate floating-point operations with fixed-point computation to realize the idea of floating point arithmetic.