I have been studying your math.  Thanks for all the help you give us all.  I thought I would give you feedback.  Your explanations are clear and easy to understand.  I remember sitting in some marketing classes and people would just say their cost was a certain set amount like say $.70.  I was sitting there thinking….mine changes almost everyday.   The more weight we gained the smaller the costs became.  I finally decided these people must run 10,000 stockers or something.  Then I found myself making all marketing decisions based on my cost of gain rather than watching the market.  It was like a disease, and only when my cost got low enough would we ever consider selling.  Luckily, you picked up on this and made this rash statement and it was like getting a giant shot in rear….”if you always sold overvalued and bought undervalued, you would probably never need to even know your cost of gain.”(Bud Williams).  I realized right then that you were trying to help me see that I was ignoring the important thing and focusing on a minor issue.  I think maybe the cattle square is responsible for this because it doesn’t work really well with little or no weight gain, so it is tempting to hold on to overvalued animals waiting until it does work, meanwhile passing up profit potential.