Below are two banners:
Chinese youth Cup competition friendship Practice Pythagorean theorem
Descendants of the Yellow Emperor Huizhou promote aspirations Revitalize China
Each character represents a non-zero natural number less than 25, different characters represent different numbers, and the same character represents the same number. It is known that the average value of the 34 numbers represented by these characters is 12. What is the maximum sum of the natural numbers represented by the characters "China"?
28. Answer: 46

Analysis: The average value of the 24 natural numbers represented by these characters is $12 \frac{14}{24}=\frac{302}{24}$, so the sum of these 24 numbers is 302. If the 24 characters each represent the numbers 1 to 24, their total sum is
$$
1+2+3+\cdots 23+24=\frac{25 \times 24}{2}=300,
$$

Since $302-300=2$, the characters “Zhong” and “Hua” each appear twice, while all other characters appear only once. This means that one of the “Zhong” or “Hua” characters must have replaced two different characters, increasing the total sum by 2.

Let $\mathrm{x}$ and $\mathrm{y}$ represent “Zhong” and “Hua” respectively, and the two characters they replace be $\mathrm{u}$ and $\mathrm{v}$. We should have:
$$
x+y=2+u+v .
$$

To maximize $x+y$, we need to maximize $u+v$.
$$
\begin{array}{l}
x+y \leqslant 23+24-47 \\
u+v \leqslant 47+2-45
\end{array}
$$

If $x+y=47$, it can only be $x=24, y=23$, or $z=23, y=24$. In this case, $u+v=45$, which can only be $u=23, v=22$, or $u=24, v=21$, leading to the situation where $y=u$, so $x+y=47$ cannot be achieved. Next, consider $x+y=46$, which can be $x=24, y=22$. By $u+v=44$, we can take $u=21, v=23$.

Thus, $x+y=46$ can be achieved.
Therefore, the maximum value of the sum of the natural numbers represented by “Zhong” and “Hua” is 46.