104 RPN Calc is a pretty friendly calculator licensed under the GPLv3.

It's good because it uses the Reverse Polish Notation.
It's better because you can manipulate the stack to drop numbers or reorganize them.
It's the best because you can write full mathematical expressions using the normal Infix Notation. Really, check the screenshots.

So you can install it now and enjoy its features:

☞ Basic operations ( + × √ … )
☞ Usual functions ( floor exp factorial log x̅ Σ Σn … )
☞ Trigonometric functions ( sin acos tanh rad→deg … )
☞ Extra functions ( surface of triangle or circle , hypot , quadratic equation … )
☞ History saver to go back and forward ( ↶ ↷ )
☞ Dragging numbers to reorder them in the stack
☞ Support for quite big numbers
☞ Permissions: With read|write_external_storage, it saves the stack in the device so the results are never lost between sessions

&& AND &&

☞ No nonsense, no cryptic buttons, not an ugly calculator anymore
☞ Well, the hyperbolic cosine might be excesive nonsense and I've never used it in real life, but it's still included because it gives a professional air to the calculator
☞ The cuadratic equation solver, that does rock
☞ And the golden ratio, useful when you want to cut rectangles of paper and need them to be aesthetically pleasing. I mean, φ² - 2 = 1/φ, and this calculator has that! You can't do the same with π and e; «e^iπ = -1» lives somewhere else

This calculator uses the Reverse Polish Notation to perform the calculations. That is, if you want to get the surface of a circle with radius 104 you will do:

3 . 1 4 1 6 ☑ 1 0 4 x² ×

Or even easier:

1 0 4 x² π ×

The circumference becomes:

2 π 1 0 4 ×

And calculating x in «2x² + 3x - 9 = 0» is:

2 ☑ 3 ☑ - 9 SOLVE

As an alternative, you can simply use the keyboard and write:

log10(100) * sqrt(4) + pow(10, 2)

It will work.


Source repository: https://github.com/civyshk/rpncalc104k
Official website: https://civyshk.github.io/rpncalc104k/
Privacy: It never access any files out of 104 RPN Calc saved state