解:1+1/2-5/6+1/12-9/20+11/30-13/42(过程可以简化一点,但这样做简单一些,虽然过程烦锁)
=3/2-5/6+1/12-9/20+11/30-13/42
=9/6-5/6+1/12-9/20+11/30-13/42
=4/6+1/12-9/20+11/30-13/42
=8/12+1/12-9/20+11/30-13/42
=9/12-9/20+11/30-13/42
=3/4-9/20+11/30-13/42
=15/20-9/20+11/30-13/42
=6/20+11/30-13/42
=3/10+11/30-13/42
=9/30+11/30-13/42
=20/30-13/42
=2/3-13/42
=28/42-13/42
=15/42
=5/14
1+1/2-5/6+1/12-9/20+11/30-13/42=1+(6-10+12)/12+(22-27)/60-13/42=1-5/12-1/12+13/42=1-1/2+13/42=1/2+13/42=34/42=17/21.
1+1/2-5/6+1/12-9/20+11/30-13/42
=1+1/2-(1/2+1/3)+(1/3-1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)
=1-1/4-1/4-1/7
=5/14