To complete the square for the polynomial \( k^2 - 16k \), we first need to determine the term that will make it a perfect-square quadratic.
- Take the coefficient of \( k \), which is \(-16\).
- Divide it by 2: \(-16 / 2 = -8\).
- Square this result: \((-8)^2 = 64\).
Now, we add \( 64 \) to the polynomial:
\[ k^2 - 16k + 64 \]
Thus, the number that makes the polynomial a perfect-square quadratic is \( \boxed{64} \).
Now, we can rewrite the expression as a perfect square:
\[ k^2 - 16k + 64 = (k - 8)^2 \]