巧算(1/110*2.1*0.54*55)/54*0.21*4又1/2

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巧算(1/110*2.1*0.54*55)/54*0.21*4又1/2
巧算(1/110*2.1*0.54*55)/54*0.21*4又1/2

巧算(1/110*2.1*0.54*55)/54*0.21*4又1/2
(1/110*2.1*0.54*55)/54*0.21*4又1/2
=(55×1/110)×(0.54/54)×(2.1/0.21)×4.5
=1/2×0.01×10×4.5
=0.225

利用乘法交换律和结合律,化简一下。我理解题目是这样:
 (1/110*2.1*0.54*55)/(54*0.21*4又1/2)
=(55/110)*(21/21)*(54/.54)*(2/.90)     分子分母扩大1000倍
=(1/2)*1*1*(1/45)
=1/90