412×113+45×598400-108×42.5+3.5÷0.5×5.2(1+0.78×56)÷(145+34)[235+2.4×(123-1.5)]÷1.1(12+999+99)÷[56×(37-38)].-数学
题文
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答案
(1)
=
=
=25
(2)8400-108×42 =8400-(100+8)×42, =8400-[100×42+42×8], =8400-[4200+336], =8400-4200-336, =3864; (3)5+3.5÷0.5×5.2 =5+7×5.2, =5+36.4, =41.4; (4)(1+0.78×
=(1+0.65)÷(145+0.75), =1.65÷145.75 =
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