Problem - 2864
Find the largest integer not exceeding $1 + \frac{1}{\sqrt{2}}+ \frac{1}{\sqrt{3}} + \cdots + + \frac{1}{\sqrt{10000}}$
It is easy to verify that$$\frac{2}{\sqrt{n+1}+\sqrt{n}} < \frac{1}{\sqrt{n}} <\frac{2}{\sqrt{n}+\sqrt{n-1}} $$
Simplifying the left and the right sides gives: $$2(\sqrt{n+1} - \sqrt{n}) < \frac{1}{\sqrt{n}} < 2(\sqrt{n}-\sqrt{n-1})$$ Hence
$$\begin{array}{rccl}
1&=& 1 &=&1\\
2(\sqrt{3} -\sqrt{2}) &<& \frac{1}{\sqrt{2}} &<& 2(\sqrt{2} - \sqrt{1})\\
2(\sqrt{4} -\sqrt{3}) &<& \frac{1}{\sqrt{3}}&<&2(\sqrt{3} - \sqrt{2})\\
& \cdots &\\
2(\sqrt{n+1} -\sqrt{n})& <& \frac{1}{\sqrt{n}} &<& 2(\sqrt{n} - \sqrt{n-1})
\end{array}$$
Adding these relations together gives $$2\sqrt{n+1}-2\sqrt{2}+1< 1 + \frac{1}{\sqrt{2}}+ \frac{1}{\sqrt{3}} + \cdots + + \frac{1}{\sqrt{n}} < 2\sqrt{n}-2+1$$
Setting $n=10000$ gives
$$\begin{array}{rcccl}
2\sqrt{10001} -2\sqrt{2}+1 &<& 1 + \frac{1}{\sqrt{2}}+ \frac{1}{\sqrt{3}} + \cdots + + \frac{1}{\sqrt{10000}} &<& 2\sqrt{10000}-1\\
198.1... &<& 1 + \frac{1}{\sqrt{2}}+ \frac{1}{\sqrt{3}} + \cdots + + \frac{1}{\sqrt{10000}} &<& 199
\end{array}$$
Therefore the answer is $\boxed{198}$.