This is a clear way to explain residual land value — working backwards from what the finished development is worth, instead of starting with the asking price, changes the whole conversation. The worked example lands well: a $10 million completed value, $2 million of required profit, and a residual of about $1.97 million makes it obvious why a $2.1 million asking price doesn't work on those assumptions.

I also appreciated the honest limits section. Profit as a percentage of GDV versus a percentage of costs is one of those details that quietly changes the answer, and timing and financing costs are where a simple model usually meets reality. Using Decimal and testing the calculation properly is the right call for money like this. Thanks for making the maths visible instead of hiding it in a spreadsheet.