http://www.khanacademy.org/math/geometry/basic-geometry/circum_area_circles/v/circles--radius--diameter-and-circumference
Watch this teaching video. Take notes; replay if needed; work it out.
Then let the math tutors know the answers you come up with. Someone will then be able to check your work for you.
find the circumference of a circle whose radius is:
1. 8 inches
2. 4 inches
1 answer