Random example off the top of my head to show off some features: say it takes 5 minutes to get to space, and I heard you come around every 90 minutes, but there's differing definitions on whether space is 80 or 100 km above the surface, then if you're curious about the G forces during launch:

    (2*pi*(6350+ 90±10)km / 90 minutes) / 5 minutes to gees
    
    ((2 × pi × ((6350 + 90±10) kilometers)) / (90 minutes)) / (5 minutes) ≈
      2.5470±0.0040 gees

It understands unicode plusminus for uncertainty tracking, units, function calls like log(n,base), find factors, it will do currencies too if you let it download a table from the internet... I love this software package. (No affiliation, just a happy user who discovered this way too late in life)

It's not as clever as WolframAlpha, no natural language parsing or Pokédex functions (sometimes I do wish that it knew things like Earth radii), but it also runs anywhere and never tells you the computation took too long and so was cancelled

Edit: I just learned there's now also an Android app! https://github.com/jherkenhoff/qalculate-android | https://f-droid.org/packages/com.jherkenhoff.qalculate/ I've checked before and there wasn't back then, so this is cool. This version says it supports graph plotting which the command-line version doesn't do