



 
Hi Ally, I think you should have both measurements in the same units so express the diameter in millimeters. If $C$ is the circumference of a circle and $d$ is its diameter then $C = \pi\;d.$ What is the circumference of your cylinder? How many times will a thread of length 143 mm go around that circumference? Penny 



Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 