To calculate the circumference, you can use the formula:

Where C is the circumference and r is the radius.
Then, you can follow the steps.
1. Substitute the radius in the equation.
In this exercise, r = 40 inches.

2. To get the approximate result, use π= 3.14 and multiplicate it in the equation.

Done! You found the circumference.
Answer: 251.2 in².