原式= (1+2+...+9) -(1/2+2/2+3/2+...+8/2) +(1/3+2/3+...+7/3) -(1/4+2/4+...+6/4) +(1/5+...+5/5) -(1/6+...+4/6) +(1/7+2/7+3/7) -(1/8+2/8) +1/9 =45-36/2+28/3-21/4+15/5-10/6+6/7-3/8+1/9 =33+5/504