15.6×2+9.8×1.56这道题的简便方法=31.2+1.56×10-1.56×0.2=31.2+15.6-0.312=46.488
解: 15.6×2+9.8×1.56=31.2+(10-0.2)*1.56=31.2+15.6-0.312=46.8-0.312=46.488
