1.1/12+1/20/1/30+1/42+1/56
=1/3-1/4+1/4-1/5+1/6-1/7+1/7-1/8
=1/3-1/8
=5/24
2.原式=1+1/10+3+1/40+5+1/88+7+1/154+9+1/238+11+1/340
=1+3+5+7+9+11+1/10+1/40/+1/88+1/154+1/1/238+1/340
=36+1/3*（1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20）
=36+1/3*（1/2-1/20）
=36+1/3*9/20
=36+3/20
=36又20分3
