The formula for circumference of a circle is πd.
I'm not sure if your teacher has specified if they would like you to use 22/7, 3.14, or the π button on a calculator, so I'l just do all of them.
22/7*4 = 88/7, or 12 4/7. If you were to use 22/7, the circumference would be approximately 12 4/7 inches.
3.14*4 = 12.56. If you were to use 3.14, the circumference would be approximately 12.56 inches.
If you were to use the π button on a calculator, the circumference, rounded to the nearest hundredth, would be approximately 12.57 inches.
Hope that helped you!
