[ArtWomb]

Quickest? Just fire up a Python REPL ;) You can even use repl.it online in lieu of shell

For simulations, computational geometry, computational probability. I prefer Golang scripts. You can subdivide computation using goroutine workers. And it's blazingly fast

That said, there is literally no downside to gaining some proficiency with professional tools: Sage / Octave, Matlab, Mathematica, SciPy