The MS Excel guru Hans Cronander presents models for R.L. McCoy / Gavre exterior ballistics and Black & Scholes / Monte Carlo option value determination. The source code includes an ODE engine based on a Bulrish-Stoer variable step length numerical integration method for rational functions. Anyone devoted to VBA programming is welcome to further develop these calculators, as long as they share the improved code with the author (the 3DOF model needs to be complemented with more retardation functions).