用简便方法计算。①4×0.8×2.5×12.5②0.65×14+87×65%-65%③42÷[14-(50-39)]④2.25×4.8+77.5×0.48
竖式计算:
竖式计算: 108×8= 807×2=
竖式计算: 315×3= 404×3=