1/42+1/56+1/90+1/110+1/132
=1/6-1/7+1/7-1/8+1/9-1/10+1/10-1/11+1/11-1/12
=1/6-1/8+1/9-1/12
=12/72-9/72+8/72-6/72
=5/72