Maybe you've heard that RPN allows calculations to be entered with fewer keystrokes. This is certainly true, although it's not the only good reason for switching over from standard "algebraic entry" calculators to an RPN calculator. Let's look at an example use case to see exactly why RPN is so great:

Tom works 3.6 hours in the morning, and 4.5 hours in the afternoon. He gets paid $14.30/hr. How much money did he make? In a standard calculator, the calculation entry would look something like this:

```
User Entry: Result:
----------- -------
(3.25 + 4.5) * 14.30 = 115.83
```

Any calculator should get you that result pretty easily (although RPN will save you a couple of keystrokes - see below). But what if you also want to know how many hours Tom worked? Typically, you wind up doing two calculations, something like this:

```
User Entry: Result:
----------- -------
3.25 + 4.5 = 7.75
[ans] * 14.30 = 115.83
```

It's a workable way to do calculations, but it's not exactly efficient. Now, let's look at how the original calculation would be entered using RPN. In RPN, you always enter the data that you want to use on the stack, and then you enter the operation that you want performed and the data is replaced by the result.

```
User Entry: Stack Display:
---------- -------------
3.25 [enter] 3.25 // First entry added on stack (morning hours)
4.5 3.25 4.5 // Second entry (afternoon hours)
+ 7.75 // replace stack entries with intermediate result (total hours)
14.30 7.75 14.30 // new entry (pay rate)
* 115.83 // replace previous result and new entry with final result
```

Notice that a couple of keystrokes were saved because there was
no need to enter parentheses.
Also, after hitting the "+" key, the stack displayed the intermediate
result - total hours worked - without having to hit "=".
This is one of the great advantages of RPN.
*Every intermediate result is displayed as the calculation is entered.*
So, you get access to more information, even though the calculation entry requires fewer
keystrokes than standard algebraic entry calculators.

RPN is great because it takes fewer keystrokes and it displays intermediate results on the fly. However, when you're done entering a calculation using a regular RPN calculator you can't verify that you entered the calculation correctly because all the original numbers on the stack were replaced with calculation results as you went.

Now, look at the screenshot at the top of the page for Visual RPN Calculator. Notice how you not only see the calculation results, but you also see the calculations that led to that results in simple to read textbook format. These calculations were entered in RPN, but rather than just calculating an answer, the calculator also built a visual image of the calculation. If you want to edit the calculation, you can click on any number and change it. If you want to split up the calculation, look at intermediate results, then put it back together again, you can. You can copy entries on the stack, move them around, label them, do all sorts of things that you can't do on a regular calculator whether it's RPN or not.

Visual RPN Calculator is more than a simple calculator. It's a tool for working with calculations in a way that supports your workflow. You can work on multiple calculations at once, combine them together, separate them, move them around, and easily go back and make changes.

If you want to see what Visual RPN Calculator can do, take a look at the Built In Help.

The first windows store submission back in July 2016 was pretty basic, but over time more features have been added on a regular basis - sometimes in response to requests from users (if you want something, click on the feedback button on the calculator under the hamburger menu or email john@linstrum.net).

Over time Visual RPN Calculator's feature set has been slowly building up to approach the calculators which cost lots of money at the store:

- All the common scientific, trig, and statistics functions - this was the easy part because they're all built into the programming language
- Extensive editing capabilities - change numbers in calculations, undo calculations and copy and move entries around on the stack
- Sets - work with numbers combined into sets, making possible single calculations using multiple data points. This is a super powerful feature once you start using it.
- Graphing - graph multiple equations at once, with highlight marks and pop-up labels for roots, graph intersects, and local minimums/maximums
- Powerful and elegant functional programming.
- Exact mode - for instance √8 = 2√2, 1/2 + 1/3 = 5/6, etc.
- Ability to enter all the commands just using the keyboard (e.g. type sin, sqrt, etc. to execute those functions). Also, lots of keyboard shortcuts so if you're working on a PC you can keep your hands on the keyboard and not use the GUI at all if you want.
- One button interface with Wolfram Alpha so you can send formulas over to their online website for more detailed analysis.

Functional programming was just implemented on the calculator, which means there's still a lot of additional features to add like better string manipulation, input dialogs, etc. Once that is handled, the next item will probably be implementing matrices.

Visual RPN Calculator has an option to store and load calculator state to files and folders of the users choice. Also, the app has access to the internet so it can send formulas to the Wolfram Alpha website and so it can access this webpage, though it also works fine without internet. Other than that, the application doesn't mess with any of your files, and no other data from your computer is ever accessed by this application or shared over the internet.