0.64*25*7.8+2.2这道题用简便方法应该怎么做
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0.64*25*7.8+2.2这道题用简便方法应该怎么做
![0.64*25*7.8+2.2这道题用简便方法应该怎么做](/uploads/image/z/8148879-63-9.jpg?t=0.64%2A25%2A7.8%2B2.2%E8%BF%99%E9%81%93%E9%A2%98%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E5%BA%94%E8%AF%A5%E6%80%8E%E4%B9%88%E5%81%9A)
0.64*25*7.8+2.2
=4×0.16×25×7.8+2.2
=(4×25)×0.16×7.8+2.2
=100×0.16×7.8+2.2
=16×7.8+2.2
=15×7.8+7.8+2.2
=15×(8-0.2)+10
=15×8-15×0.2+10
=120-3+10
=127
=4×0.16×25×7.8+2.2
=(4×25)×0.16×7.8+2.2
=100×0.16×7.8+2.2
=16×7.8+2.2
=15×7.8+7.8+2.2
=15×(8-0.2)+10
=15×8-15×0.2+10
=120-3+10
=127