1. The problem is to express $\sqrt{16}$ as an exponent. 2. Recall that the square root of a number can be written as an exponent with a fractional power: $\sqrt{a} = a^{\frac{1}{2}}$. 3. Applying this rule to $\sqrt{16}$, we write it as $16^{\frac{1}{2}}$. 4. To verify, calculate $16^{\frac{1}{2}} = \sqrt{16} = 4$. 5. Therefore, $\sqrt{16}$ written as an exponent is $16^{\frac{1}{2}}$. Final answer: $16^{\frac{1}{2}}$