Have seen Excel derivatives pricers that ran long Monte Carlo simulations (yes, RAND() is often good enough) that took several minutes -- press F9 for a new est

Have seen Excel derivatives pricers that ran long Monte Carlo simulations (yes, RAND() is often good enough) that took several minutes -- press F9 for a new estimate of a price, as well as simplified stripped-down pricers that got within 0.001% of our real internal pricing system but was nicely laid out and explainable to clients. The only thing that Excel is awkward at is unlimited recursion. For everything else, if you can't turn your computation into a nicely laid-out spreadsheet, then you probably don't understand your problem well enough to explain to others. Had a fun time doing many of the Euler problems in Excel, even though they theoretically many require recursion. Oftentimes I got the answer more quickly and easily than in Python.