用简便方法计算2.5×9.9十2.5
原式=2.5×(9.9+1)
=2.5×(10+1-0.1)
=25+2.5-0.25
=25+2.25
=27.25
=2.5×(10+1-0.1)
=25+2.5-0.25
=25+2.25
=27.25
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第1个回答 2018-01-20
2.5×9.9十2.5
=2.5×（10-0.1）+2.5
=25-0.25+2.5
=25+2.5-0.25
=27.5-0.25
=27.25本回答被网友采纳
=2.5×（10-0.1）+2.5
=25-0.25+2.5
=25+2.5-0.25
=27.5-0.25
=27.25本回答被网友采纳
第2个回答 2018-01-20
2.5×9.9十2.5 =2.5*（9.9+1）=2.5*（10+0.9）
=25-2.25=22.75
=25-2.25=22.75
第3个回答 2018-01-20
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第4个回答 2018-01-20
解：原式=2.5*（10-0.1）+2.5
=25-0.25+2.5
=25+2.5-0.25
=25+（2+0.5）-0.25
=25+2+（0.5-0.25）
=27+0.25
=27.25
=25-0.25+2.5
=25+2.5-0.25
=25+（2+0.5）-0.25
=25+2+（0.5-0.25）
=27+0.25
=27.25
