| 下面各题怎样简便就怎样算. ①0.25×1.58×4 ②18.5×0.8-8.5×0.8 ③3.6÷[(17.3+30.7)×0.25] ④4.9÷25÷0.4. |
| ①0.25×1.58×4 =(0.25×4)×1.58 =1×1.58 =1.58 ②18.5×0.8-8.5×0.8 =(18.5-8.5)×0.8 =10×0.8 =8 ③3.6÷[(17.3+30.7)×0.25] =3.6÷[48×0.25] =3.6÷[12×(4×0.25)] =3.6÷[12×1] =3.6÷12 =0.3 ④4.9÷25÷0.4 =4.9÷(25×0.4) =4.9÷10 =0.49 |
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