* Not part of the cattle square — added because it is the number most ranchers already reason in. It is the same excess profit per head, measured against the whole sale instead of against the value of the gain: (sale − (purchase + BPCtK × lbs of gain)) ÷ sale. On the worked example at 20% profit that is $990.00 − ($580.50 + $0.96 × 320 lb) = $102.30, and $102.30 ÷ $990.00 = 10.3%, where the square's own margin reads 25.0%. Both are right; they answer different questions. The square's margin is the one this system ranks and alerts on, because it measures the trade itself rather than how much money the animal tied up.