Hyper thread what bull s-hit answer is that? Here is how it works ;) 1. Light one thread at both ends and the other at one end at the same time. Since it takes 1 hour to completely burn one thread if you light it at one end, it should take exactly 1/2 hour for it to burn completely if you light it at both ends at the same time. 2. The other end of the second thread should be lighted at the same time when the first thread completely burn out. The complete burn out of the second thread should give you 15 mins 3. 30 min + 15 min = 45min