2.5×9.8=2.5X(10—0.2)=2.5X10—2.5X0.2=25—0.5=24.5 1.25×25×3.2=1.25X25X4X8=(1.25X4)X(8X25)=0.5X200=100
1.2×2.5+0.08×25=1.2×2.5+0.8×2.5=(1.2+0.8)×2.5=2×2.5=5
1.2x2.5 =1.2×1/4=0.3 0.08x25=0.08×100÷4=2
0.08X25用竖式计算什么算