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数的运算(2)
1. 脱式计算。
234-178+341 5.6÷0.4×12 56×17×23
23+45÷3 23+27×73 119×[12÷(65+1)]
2.用简便方法的计算下面各题。
160+39+61 358-67-133 25×0.67×4
3.72×3.5+6.28×3.5 0.56×99+0.56 3200÷125÷8
3.妈妈买了4箱饮料,每箱有24瓶,每瓶2.5元,一共共了多少元钱?
答案
1.234-178+341 5.6÷0.4×12 56×17×23
=56+344 =14×12 =8×23
=397 =168 =163
23+45÷3 23+27×73 119×[12÷(65+1)]
=23+15 =23+23 =119×[12÷115]
=38 =43 =119×522
=518
2.160+39+61 358-67-133 25×0.67×4
=160+(39+61) =358-(67+133) =25×4×0.67
=160+100 =358-200 =100×0.67
=260 =158 =67
3.72×3.5+6.28×3.5 0.56×99+0.56 3200÷125÷8
=(3.72+6.28)×3.5 =0.56×99+0.56×1 =3200÷(125×8)
=10×3.5 =0.56×(99+1) =3200÷1000
=35 =0.56×100 =3.2
=56
3.4×24×2.5
=4×2.5×24
=10×24
=240(元)
答:一共花了240元钱。
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