From the perspective of an end user thinking in tools rather than in software packages, the poll doesn't have two very used ones: (pocket like) calculator(s) and spreadsheets.
To me, the most frequently used numerical programs are (mostly needed for Electrical Engineering):
1. Pocket-like calculators, either physical (e.g. Casio fx-991ES), or some similar programs
2. Spreadsheets
3. Dedicated CAD-EDA tools (e.g. LTspice, QucsStudio)
QucsStudio is particularly nice because it allows one to attach sliders for various values, like in this random example (two coupled resonators showing the influence of coupling factor over the two resonant frequency peaks):
View: https://www.youtube.com/watch?v=fYs7ZoVyPmM
4. Numpy+Matplotlib or alike Python based, like Scipy or JupyterLab/Notebooks
To me, Python is probably the most used tool nowadays when it comes to program something that needs numeric processing. Random example of a curve tracer improvised with Python controlling physical instruments (this one made in JupyterLab):
https://www.eevblog.com/forum/testgear/rigol-dp832-power-supply-as-automated-curve-tracer/
5. Geogebra, very nice because it has both offline and online versions, and lets one to share interactive plots, formulas, geometry in 2D or 3D, even lets you to embed live demos if a forum or whatever other platform allows iframes.
Random example of an interactive plot in Geogebra:
Gaussian
www.geogebra.org
6. Other: Octave, LabVIEW (rather rare)
Later edit:
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And in general, the tool depends of whatever I want to solve, funny fact I remember now how once I've used a game engine (
pygame) to illustrate one of my ideas about how to "watch" outside the observable Universe, however, the physicists were keep telling me this wouldn't work, grrr, but it should work, look!
View: https://www.youtube.com/watch?v=BjbNZ7SLzwM