The ﬁve numbers $17$, $98$, $39$, $54$, and $n$ have a mean equal to $n$. Find $n$.
1. We are given five numbers: $17$, $98$, $39$, $54$, and $n$. The mean of these numbers is equal to $n$.
2. The mean of a set of numbers is calculated by dividing the sum of the numbers by the number of elements in the set. Therefore, we have:
   \[
   \frac{17 + 98 + 39 + 54 + n}{5} = n
   \]
3. Simplify the sum in the numerator:
   \[
   \frac{208 + n}{5} = n
   \]
4. To eliminate the fraction, multiply both sides of the equation by $5$:
   \[
   208 + n = 5n
   \]
5. Subtract $n$ from both sides to isolate the variable $n$:
   \[
   208 = 4n
   \]
6. Divide both sides by $4$ to solve for $n$:
   \[
   n = \frac{208}{4} = 52
   \]

The final answer is $\boxed{52}$