16. \( \frac{d^{6}}{d^{11}} \)

The expression \( \frac{d^{6}}{d^{11}} \) seems to involve differentiation, but it is not a standard notation in calculus. Typically, \( \frac{d^n}{dx^n} \) represents the \( n \)-th derivative with respect to \( x \). If we interpret \( \frac{d^{6}}{d^{11}} \) as a ratio of derivatives, it could imply taking the 6th derivative and then dividing by the 11th derivative, but this is not a conventional operation. If you meant to ask about the relationship between the 6th and 11th derivatives of a function, we can say that the 11th derivative of a function is simply the derivative taken 11 times, and the 6th derivative is taken 6 times. However, without a specific function or context, we cannot simplify or evaluate this expression further. If you have a specific function in mind or a different interpretation of the expression, please provide more details!