To find the circumference \( C \) of a circle with a diameter of 16 feet using the formula \( C = \pi d \), we can substitute \( \pi \) with 3.14 and \( d \) with 16 feet.
\[ C = 3.14 \times 16 \]
Now, perform the multiplication:
\[ C = 3.14 \times 16 = 50.24 \]
Thus, the circumference \( C \) is:
\[ C = 50.24 , \text{ft} \]