What is the formula for the summation of: 1 / n(n+1)

Thank youuu!

... Σ [ 1 / (r(r+1)) ], ........... r = 1, ... ,n

= Σ [ (1/r) - (1/(r+1)) ]

= (1/1 - 1/2) + (1/2 - 1/3) + (1/3 - 1/4) + ... (1/n - 1/(n+1))

= (1/1 - 1/(n+1))

= n/(n+1) ........................................… Ans.
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