I like calc paired with gnuplot.
inb4 dc(1)/bc(1)... calc supports complex numbers, C-like pseudo structures/functions, custom decimal points and lots more.
Also, calc/gnuplot will run on a toaster or even legacy systems from 20-25 years ago.
You need to be very careful, as you may get wrong results due to rounding and floating point errors.
$ node -i
> 2**54+2
18014398509481984
> 3-3.01
-0.009999999999999787
Even proer tip: https://github.com/lcn2/calc
Can't live without that one in $PATH.