巧算:1/2+1/6+1/12+1/20+1/30=?
巧算1道数学题1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
巧算:2/1-6/1-12/1-20/1-30/1-42/1-56/1-72/1
巧算:1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
巧算1/6 1/12 1/20 1/30 1/42 1/56
1/2+1/6+1/12+1\20+1/30+1/42+.+1/9900=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56=?
2/1+6/1+12/1+20/1+30/1+42/1+56/1=
2/1+6/1+12/1+20/1+30/1+42/1+56/1=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56=
1+1/2+1/6+1/12+1/20+1/30+1/42=?
1/2,-1/6,1/12,-1/20,1/30
1/2+1/6+1/12+1/20+1/30