Let the rest energy of a particle be $E$. Let the work done to increase the speed of this particle from rest to $v$ be $W$. If $W = \frac{13}{40} E$, then $v = kc$, where $k$ is a constant. Find $10000k$ and round to the nearest whole number.

Let's think step by step and output the final answer within \boxed{}.
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