三乘五分之二＋五乘七分之二＋七乘九分之二＋九乘十一分之二＋…＋九十九乘一百零一分之
=1/3-1/5+1/5-1/7+1/7-1/9+……+1/99-1/101
=1/3-1/101
=98/303