$\left( \sqrt{17.8} \right)^2 = 17.8$

Since the square of a square root cancels out the square root itself, the answer is simply 17.8.

Would you like more details on this concept or have any questions?

Here are five related questions:

1. What is the square of $\sqrt{25}$?
2. Simplify $\left(\sqrt{7}\right)^2$.
3. What is $\sqrt{x^2}$ when $x = 9$?
4. How do you simplify $\left(\sqrt{a}\right)^2$ for any positive real number $a$?
5. Solve $\left( \sqrt{49.5} \right)^2$.

Tip: The square of a square root always returns the original value inside the root, assuming the value is non-negative.