1. **Problem:** Find the sum of the series $$\frac{1}{2} + \frac{2}{3} + \frac{3}{4} + \frac{4}{5} + \dots$$
2. **Understanding the series:** Each term is of the form $$\frac{n}{n+1}$$ where $$n$$ starts from 1 and goes to infinity (or some finite number).
3. **Formula and simplification:** We can rewrite each term as:
$$\frac{n}{n+1} = 1 - \frac{1}{n+1}$$
4. **Sum of first $$N$$ terms:**
$$S_N = \sum_{n=1}^N \frac{n}{n+1} = \sum_{n=1}^N \left(1 - \frac{1}{n+1}\right) = \sum_{n=1}^N 1 - \sum_{n=1}^N \frac{1}{n+1}$$
5. **Evaluate sums:**
$$\sum_{n=1}^N 1 = N$$
$$\sum_{n=1}^N \frac{1}{n+1} = \sum_{k=2}^{N+1} \frac{1}{k} = H_{N+1} - 1$$
where $$H_m$$ is the $$m$$-th harmonic number.
6. **Combine results:**
$$S_N = N - (H_{N+1} - 1) = N + 1 - H_{N+1}$$
7. **Interpretation:** The sum of the first $$N$$ terms is $$S_N = N + 1 - H_{N+1}$$.
8. **If infinite sum:** Since harmonic numbers grow without bound, the infinite sum diverges.
**Final answer:**
$$\boxed{S_N = N + 1 - H_{N+1}}$$
Sum Fraction Series 70A363
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