Evaluate $16^{7/4}$.
To evaluate $16^{7/4}$, I need to apply the rules of exponents for fractional powers. One way to do this is to write $16^{7/4}$ as $(16^{1/4})^7$, since $(a^b)^c = a^{bc}$. Then, I need to find $16^{1/4}$, which is the same as the fourth root of 16. I know that the fourth root of 16 is 2, since $2^4 = 16$. Therefore, $16^{1/4} = 2$ and $16^{7/4} = (16^{1/4})^7 = 2^7$. Finally, I need to calculate $2^7$, which is $2 \times 2 \times 2 \times 2 \times 2 \times 2 \times 2 = 128$. 