2/3+4/5+6/7+8/9+10/11+12/13+.+60/61=1-1/3+1-1/5+1-1/7+.+1-1/61=1+1+1+.-1/3-1/5-1/7-.-1/61=30-1/3-1/5-1/7-.-1/61=30-(1/3+1/5+1/7+.+1/61)≈30-1.69877029=28.30122971