The diameter of a circle is 3 centimeters. What is the
circumference?

Circumference of circle formula = pi x diameter

so,
pi x 3 = 3 pi
( if you want the answers in terms of pi )

if pi = 3.14,
3.14 x 3 = 9.42

if pi = calculator pi,
pi x 3
= 9.42477796...
≈ 9.42 ( 3 dp )

ps i do not know what the question wants you to use what value of pi, so i included all 3 of the methods here. hope this helps.