项数和=(首项+末项)x项数 =(首项+末项)x{(末项-首项)/公差+1} =(0.1+0.9)×{(0.9-0.1)/0.2+1} =1×5=5 (0.11+0.99)×{(0.99-0.11)/0.02+1} =1.1×(0.88/0.22+1) =1.1×45 =49.5 49.5+5=54.5
简算0·1十0·3····十0·9十0·11十0·13十0·15···十0·97十0·99
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相关问题
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0.|十0.2十0.3十0.4十0.5十0.6十0.7十0.8十0.9怎样巧算
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提问:0,01十0.02十0.03…o,97十O,98+0.99=
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1.(1十0.23十0.34)*(0.23十0.34十0.56)一(1十0.23十0.34十0.56)*(0.23十0.
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(1十0.23十0.45)x(0.45十o.67十0.89)一(1十0.45十0.67十0.89
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O十0=△十口 △=0十口 那么△十0=几个口步骤,必采纳
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简便方法计算 0.9+9.9十99.9十999.9十9999.9
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0十0十口=12.7,0一囗=1.31,0x囗=?
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(a十1)十(b一2)=0
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0.99+9.9×9.9-9(1+九十七分之一)+(2+九十七分之二)+(3+九十七分之三)+.+(97+九十七分之九十