.060.003302.计算下面各种商品的总价。21.00×2.7=56.70(元)1.60×7.5=12.00(元)7.20×7.2=51.84(元)3.判断下面各个积的小数位数有没有错误。56.7×38=2154.62.8×5.6=1.5680.37×0.94=3.4781.23×29.2=359.161.56×0.9=1.4040.78×6.1=47.58×=15.68×=0.3478×=35.916×=4.7584.小娟要冲洗14张照片,每张照片冲洗费0.85元。她一共要花多少钱?14×0.85=11.9(元)答:她一共要花11.9元。5.地球直径1.28万千米,月球到地球的距离是地球直径的30倍。月球到地球有多远?1.28×30=38.4(万千米)答:月球到地球有38.4万千米。6.先计算,再验算。0.39×2.90.58×0.083.7×2000.18×8.45=1.131=740=1.521=0.04640.39×2.9351781.131验算2.9×0.39261871.1310.18×8.4590721441.5210验算:8.45×0.1867608451.52100.58×0.080.0464验算0.08×0.5864400.04643.7×200740.0验算200×3.7146740.04.5×0.0020.072×0.15=0.009=0.01080.072×0.15360720.01080验算:0.15×0.072301050.010804.5×0.0020.0090验算:0.002×4.51080.00907.世界上最大的一颗巨杉,质量是蓝鲸的18.7倍,高是蓝鲸体长的3.2倍。这颗巨杉重多少吨?高多少米?150×18.7=2805(吨)25.9×3.2=82.88(m)答:这颗巨杉重2805吨,高82.88m。体重150t,体长25.9m。
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