计算下列各题,怎样简便怎样算. 105×13﹣1890÷18 [﹣(﹣)]÷ 25×+2.75÷ 27.4﹣52.8÷(1.9+2.1) (0.125×8﹣0.5)×4 9.25×9.9+0.925
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口算。+= -= += - +=0.63×1000= 0. 75-0.25= 0.07+0.03= 0. 9÷0.03= 0.4×0.8=
×= ÷3=÷= -=3÷15= +0.25=1÷= 85%-15%=10÷10%= 5×÷5×=
脱式计算下面各题。4÷-0.6 ×÷(+)÷ ÷[1÷(-)]
÷+×