减1是因为-7.3=-7.3×17.3×3.7-7.3+0.73×73=7.3×3.7-7.3×1+7.3×7.3=7.3×(3.7-1+7.3)=7.3×10=73
7.3乘3.7减7.3加0.73乘察前举73简便悔渣计败碧算=7.3×3.7-7.3+7.3×7.3=7.3×（3.7-1+7.3）=7.3×10=73
