What is the greatest integer not exceeding the sum $$\sum_{n=1}^{1599} \frac{1}{\sqrt n}$$
I have already arrived at a solution using calculus but since this came in a Math Olympiad which do not include calculus in their syllabus I wanted to know how I could do this without it. My first thought was to use Titu's Lemma but I couldn't think of what I could do after that. Any hints will be appreciated, thanks