一、实数加、减、乘、除的意义 我们先介绍无理数的近似值。 用无限不循环小数表示的一个无理数,如果把它的十分位、百分位、千分位等后面的所有数字都舍去,就分别得到这个无理数精确到0.1、0.01、0.001等的不足近似值。如果在不足近似值的最末一位加上这一位的一个单位,就得出精确度相同的过剩近似值。 First, the meaning of real numbers add, subtract, multiply, divide We first introduce the approximate value of irrational numbers. An irrational number represented by an infinitely non-recursive decimal number, if all the digits following it, such as its tenth, hundredth, and thousandth, are rounded off, the insufficient approximation of this irrational number to 0.1, 0.01, 0.001, etc., respectively, is obtained. If one unit of this bit is added to the last bit of the near-approximation value, an approximation of the same excess accuracy is obtained.