笔算下面各题．405×28 380×45 329÷29 700÷23．
++++﹣﹣++﹣﹣ 1﹣++﹣．
计算：= 1﹣====== 1﹣===
+ =﹣ = = 改正：
用推算计算 （1）+= （2）﹣=
计算： 2.5×40= 18×6= 1.73+2.07= 10﹣0.9= 400÷4=+=﹣=+=﹣=﹣=
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1﹣
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= 1﹣
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= 1﹣
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﹣
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﹣
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