An integer is square-free if it is not divisible by $a^2$ for any integer $a>1$. Let $S$ be the set of positive square-free integers. Determine, with justification, the value of\[\sum_{k\epsilon S}\left[\sqrt{\frac{10^{10}}{k}}\right]\]where $[x]$ denote the greatest integer less than or equal to $x$
1. **Rewrite the given sum**:
   \[
   \sum_{k \in S} \left\lfloor \sqrt{\frac{10^{10}}{k}} \right\rfloor
   \]
   Here, \( S \) is the set of positive square-free integers. We need to evaluate the sum of the greatest integer less than or equal to \( \sqrt{\frac{10^{10}}{k}} \) for all \( k \in S \).

2. **Express the floor function in terms of a double sum**:
   \[
   \left\lfloor \sqrt{\frac{10^{10}}{k}} \right\rfloor = \sum_{i=1}^{\left\lfloor \sqrt{\frac{10^{10}}{k}} \right\rfloor} 1
   \]
   This means we count the number of integers \( i \) such that \( i \leq \sqrt{\frac{10^{10}}{k}} \).

3. **Rewriting the sum**:
   \[
   \sum_{k \in S} \left\lfloor \sqrt{\frac{10^{10}}{k}} \right\rfloor = \sum_{k \in S} \sum_{i=1}^{\left\lfloor \sqrt{\frac{10^{10}}{k}} \right\rfloor} 1
   \]
   This can be interpreted as counting the number of pairs \((k, i)\) such that \( k \in S \) and \( i \leq \sqrt{\frac{10^{10}}{k}} \).

4. **Change the order of summation**:
   Let \( m = k i^2 \). Then \( m \) ranges from 1 to \( 10^{10} \), and \( k \) must be a square-free divisor of \( m \). Therefore, we can rewrite the sum as:
   \[
   \sum_{m=1}^{10^{10}} \sum_{\substack{k \in S \\ k \mid m \\ k \text{ square-free}}} 1
   \]
   Here, \( k \) is a square-free divisor of \( m \).

5. **Count the number of square-free divisors**:
   Each \( m \) has a unique representation as \( k i^2 \) where \( k \) is square-free and \( i \) is an integer. The number of such pairs \((k, i)\) for each \( m \) is exactly 1, because \( k \) and \( i \) are uniquely determined by \( m \).

6. **Sum over all \( m \)**:
   Since each \( m \) from 1 to \( 10^{10} \) contributes exactly 1 to the sum, we have:
   \[
   \sum_{m=1}^{10^{10}} 1 = 10^{10}
   \]

Conclusion:
\[
\boxed{10^{10}}
\]