7.2x25x8.5用简便方法计算7.2x25x8.5=25*8*(0.9*8.5)=200*7.65=1530
7.2x25x8.5用简便方法计算=25x8x9x8.5=200x8.5x9=1700x(10-1)=17000-1700=15300
7.2x25x8.5 =1.8x(4x25)x8.5 =18x85 =1530