F = 1/3.6 + 1/6.9 + 1/9.12 + ... + 1/30.33
F = 1/3.(1.3-1/6+1/6-1/9+1/9-1/12+...+1/30-1/33)
F = 1/3.(1/3-1/33)
F = 1/3.10/33
F = 10/99
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