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Summation (Sigma) Calculator

Enter an expression in terms of k with a lower and upper index to evaluate the sigma series Σ — with the number of terms, the first and last terms, the expansion, and full step-by-step working.

Sigma notation:  Σk=ab f(k) = f(a) + f(a+1) + … + f(b)
Σ expression f(k) ,  k from lower a to upper b

Use k as the index variable. Allowed: + − * / ^, parentheses, and functions sin cos tan sqrt ln log abs exp plus pi and e. Indices must be integers with a ≤ b.

Results

Summation
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Number of terms
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First term — f(a)
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Last term — f(b)
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Expansion
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Step-by-step