Perhaps a silly question – if you were finding the IRR in practice/doing a sensitivity analysis on interest rate change etc would you ever find people using the binomial expansion and finding the solution algebraically? Or would it just be a numerical solution that is left to the computer – I imagine Excel etc has something that might be more precise than the 2 interest rates and approximate method (though appreciate that in practice there might be limited benefit to greater precision given all the other uncertainties in forecasting assumptions etc)