来自雷亚辉的问题
199.4*19.93-199.3*19.92的简便计算
199.4*19.93-199.3*19.92的简便计算
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2020-03-22 07:07
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苏正华
199.4×19.93-199.3×19.92
=(199.3+0.1)×19.93-199.3×(19.93-0.01)
=199.3×19.93+19.93×0.1-199.3×19.93+199.3×0.01
=1.993+1.993
=(2-0.007)+(2-0.007)
=4-0.014
=3.986
2020-03-22 07:12:05