Split term method: 1 / 3 + 1 / 15 + 1 / 35 + 1 / 63 + 1 / 99

=1/2(1-1/3)+1/2(1/3-1/5)+1/2(1/5-1/7)+1/2(7/1-1/9)+1/2(1/9-1/11)
=1/2(1-1/11)
=5/11
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