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MathNet 1998 — Part 01 Question 57

Math Olympiad Vault · MathNet 1998 — Part 01

Question 57

$x$ is a positive real number if $[x]$ denotes the internal part of $x$, instead of the largest integer $n \leq x$. If I trace the somma $\sum_{n=1}^{1000000} [\sqrt{n}] = [\sqrt{1}] + [\sqrt{2}] + \ldots + [\sqrt{999999}] + [\sqrt{1000000}]$.

[The students will use, it is believed, the following formula: $\sum_{i=1}^k i^2 = \frac{k(k+1)(2k+1)}{6}$, the demonstration is not required.]