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41.2乘以8.1加11乘以1.25加53.7乘以1.9的简便方法递等式

题目详情
41.2乘以8.1加11乘以1.25加53.7乘以1.9的简便方法递等式
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答案和解析
41.2×8.1+11×1.25+53.7×1.9
=41.2×(10-1.9)+(10+1)×1.25+53.7×1.9
=412-41.2×1.9+12.5+1.25+53.7×1.9
=412+(53.7-41.2)×1.9+12.5+1.25
=412+12.5×(2-0.1)+12.5+1.25
=412+25-1.25+12.5+1.25
=412+25+12.5
=449.5
或者:
41.2×8.1+11×1.25+53.7×1.9
=41.2×(10-1.9)+(10+1)×1.25+(41.2+12.5)×1.9
=412-41.2×1.9+12.5+1.25+41.2×1.9+12.5×1.9
=412+12.5+1.25+12.5×1.9
=412+12.5+1.25+12.5×(2-0.1)
=412+12.5+1.25+25-1.25
=412+37.5
=449.5