求这几道简便计算题的做法!5.555×5.2 2.22×3.33 7.658×85 36.02×0.3 56.78×8
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求这几道简便计算题的做法!5.555×5.2 2.22×3.33 7.658×85 36.02×0.3 56.78×8
求这几道简便计算题的做法!
5.555×5.2
2.22×3.33
7.658×85
36.02×0.3
56.78×8
求这几道简便计算题的做法!5.555×5.2 2.22×3.33 7.658×85 36.02×0.3 56.78×8
5.555×5.2=1.111×5×5.2=1.111×26=28.886
2.22×3.33 =1.11×2×3.33=(1+0.1+0.01)×6.66=6.66+0.666+0.0666=7.3926
7.658×85=7.658×(100-10-5)=765.8-76.58-38.29=650.93
36.02×0.3=(30+6+0.02)×0.3=9+1.8+0.006=10.806
56.78×8=56.78×(10-2)=567.8-113.56=454.24
5.555×5.2=11.11×2.6=28.886
2.22×3.33=1.11×1.11×6=1.2321×6= 7.3926
7.658×85=8×85-0.342×85=340- 2.907=337.093
36.02×0.3=36×0.3+0.02×0.3=10.8+0.006=10.806
56.78×8=56×8+0.78×8=448+6.24=454.24
有的题目简便不了多少，好算些罢了：
5.555×5.2 ＝5*1.111*5.2＝26*1.111＝28.886
2.22×3.33 ＝2.22*3*1.11＝6.66*1.11＝7.3926
7.658×85＝7.658*（100-10-5）＝765.8-76.58-38.29＝650.93
36.02×0.3 ＝10.806 （口算都可以的）
56.78×8＝56.78*（10-2）＝567.8-113.56＝454.24