Question 131
The nonzero natural numbers $n$ and $m$ satisfy $n \lt m$. Prove that
$$
S = \frac{1}{n} + \frac{1}{n+1} + \cdots + \frac{1}{m}
$$
is not a natural number.
$$
S = \frac{1}{n} + \frac{1}{n+1} + \cdots + \frac{1}{m}
$$
is not a natural number.