Expectation of Discrete Uniform Distribution

Theorem
Let $$X$$ be a discrete random variable with the discrete uniform distribution with parameter $n$.

Then the expectation of $$X$$ is given by:
 * $$E \left({X}\right) = \frac {n+1} 2$$

Proof
From the definition of expectation:
 * $$E \left({X}\right) = \sum_{x \in \operatorname{Im} \left({X}\right)} x \Pr \left({X = x}\right)$$

Thus:

$$ $$ $$ $$