Circumference is what u need. It is like perimeter and u need a fence so use circumference. It is pi times diameter. Pi * 22 = 69.12 or 69.08. Depending on how u use pi the answers will come out different. If u use the pi button on the calculator and go from there it will be about 69.12 or more if u use a graphing calculator. If u use 3.14 it will be 69.08.