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通常,只有经过严格周密地验算,才能确知运算结论正确与否。但在实际应用中,我们常常设有验算的时间和条件。本文介绍的三种简明验算法,能使我们估算运算结果的正误,提高直觉判断力。1.个位验算法。所谓个位验算法,就是对所得结果的个位进行验算,看两次计算的个位是否一致,若不一致,说明原结果错误。如判定688+(699-278)×465+28÷7=1924248计算是否正确?因为正确计算的个位应当是:8+(9-8)×5+4=7,而原计算的结果个位是8,故原计算有误。
Often, only after a rigorous and thorough examination can you determine whether the conclusion of an operation is correct or not. However, in practice, we often have time and conditions for checking. This article describes the three concise method of checking, can make us estimate the correctness of the results, improve the intuitive judgment. 1. A bit checking method. The so-called one-bit checking algorithm, that is, the result of a unit of checking to see whether the calculation of two parity, if inconsistent, indicating the original result is wrong. Such as the decision 688 + (699-278) × 465 +28 ÷ 7 = 1924248 calculation is correct? Because the correct calculation of the unit should be: 8 + (9-8) × 5 +4 = 7, and the original results of a Bit is 8, so the original calculation is wrong.