1)2 1/2*1 2/5*1 2/7*1 2/9*1 2/11+1/2 2)2 1/3*1 4/7*1 4/11*1 4/15*1 4/19-2/3

2 1/2*1 2/5*1 2/7*1 2/9*1 2/11+1/2 =(5*7*9*11)/(2*5*7*9)+1/2=11/2+1/2=12/2=6
2 1/3*1 4/7*1 4/11*1 4/15*1 4/19-2/3=(7*11*15*19*23)/(3*7*11*15*19)-2/3
=23/3-2/3=21/3=7