Tangential but I've been thinking about building a real-estate calculator after my first homebuying experience, something that will provide you with a total cost of ownership, points bydowns and other useful metrics about a home purchase. Rather than jumping into a web app to start building, I've been prototyping it in Excel. I found it really cool for prototyping this type of app, I built my entire "MVP" in about an hour and now just evaluating all the "features" I've added before committing to transplanting this into a webapp.
Yeah, at this point for a lot of the more "number heavy" things I do, my first version is generally in Google Sheets to get a rough prototype and to make sure my math is basically correct, and then a port to Julia.
The hyper-interactive nature of spreadsheets makes them kind of genuinely fun to tinker with. You can see results immediately, and you have enough logic (even in just the vanilla cells, not even counting JS or VBA) to implement a lot of algo stuff.
