A calculator may not seem like a very important app to buy for your iPhone. After all, the iPhone has a built-in calculator that is easily accessible by swiping up from the bottom of any screen. Also, I often find that the fastest way to do simple calculations is to hold down my home button to activate Siri and then ask something like "what is 93 divided by 6." But Calcbot, which was updated just a few weeks ago to version 2, is worth looking at. There is a free version so that you can get a feel for the app, but you'll want to spend $1.99 in the app to upgrade to the Pro features to get the full value from this app. It is certainly worth two bucks. Here is why.
A great calculator
Of course, Calcbot is calculator. Fortunately, it is a great calculator. What sets it apart from the iPhone's built-in calculator is the way that it shows your work and gives you an answer faster than other calculators. Let's say that you want to add 75 and 45. First tap 75, then tap the + key, and then as you type 45 — even before you hit the equal key — you already see the result (120). This is not how calculators normally work; normally you see the number that you are typing. But in Calcbot, what you are typing goes into the equation, in a small font just below the answer. In this way, you can see your work, and as you continue to add, subtract, multiply or divide other numbers your equation gets longer, but you always see the current result based on the numbers you have typed so far. Once you get used to the way that Calcbot works, it is a much better approach than what you get on other calculators because you see the answer more quickly and you always see all of the numbers that got you to that answer.
When you are done, tap the equal key, and this does two things. First, it adds the equation to the tape of prior calculations. Second, it gives you the ability to hold a finger on the result to copy it so that you an paste it elsewhere on your iPhone.
A really like the tape function of Calcbot. For each prior entry, you can see both the prior equations and the prior answers. The free version of the app limits you to the past 10 records; when you pay $1.99 to upgrade to Pro you have an unlimited history tape.
Tap on any prior calculation and you can either use the result (the final number), use the expression (bring the equation back so that you can do even more calculations), copy the answer, or send as an email the entire equation plus the answer. And if you want to see more than the last two entries in the tape, just swipe down from the top of the screen to see the full history.
When you are looking an entries in the tape, you can tap a star next to any of them to make it a favorite. That way, in the future, you can tap on the star button on the calculator to see prior results that you have made a favorite. It is like the memory function on a typical calculator, except that you typically get only one number in memory (and you have to remember what it is), whereas in Calcbot you can have lots of numbers in memory and you can see what each of them is and select just the one that you want.
If you turn your iPhone to landscape orientation, you get scientific functions. That's not something that I ever use as a lawyer or in my every day life — I don't think that I have used the sine or cosine function since high school — but if you want it, there it is.
Unit Conversion
Calcbot is a fantastic calculator, but that is only half of what it does. After you spend $1.99 to upgrade to the Pro version, you gain access to the other half of the app: unit conversion. Swipe your finger across the main part of the app (where the numbers appear) to switch to unit conversion mode. For example, type the number 78 and then swipe from left to right to change to unit conversion mode. You will then see icons representing different units. If you are in the currency mode, the app can tell you, for example, that $78 in U.S. currency is currently equal to €71.94. Swipe up and down to change the currency you are converting from and you are converting to. Or swipe up and down on the icons on the left to change to other categories such as weather (e.g. Fahrenheit to Celsius), weight (e.g. ounce to gallon), area (e.g. acre to square mile), etc. Just about any type of unit conversion that you might want to do is just a few swipes away.
Etc.
The app has some other features that you might find useful. Although I like the default theme, you can change it if you want. When you upgrade to Pro you can select the Pro theme, or you can purchase optional theme packs.
Although I normally keep the sounds off for virtually every app on my iPhone, Calcbot is one of the very rare apps that I permit to make noise, because the sounds provide feedback as you are entering numbers and getting results, and the sounds used by the app are noticeable but not obnoxious.
You can also clear your history tape or send the entire history tape as an email. And if you are dealing with currency you can opt to have all of your calculations rounded off to two decimal places.
All of these are minor but nice touches that make it that much better of an app overall.
iPad version
This is a universal app, so it also works on the iPad — useful because the iPad, unlike the iPhone, doesn't come with a built-in calculator. Although I do like Calcbot on the iPad, especially all of the advanced features that I mentioned above, I typically use my iPad in landscape orientation, and I don't like that this means that I always see those scientific function buttons, buttons that I never use.
I wish instead there were an option to just display larger keys. For example, I am a big fan the large iPad buttons in the Digits app.
Having said that, one thing that is really nice about the iPad app is that both the iPhone and iPad apps share and sync the history tape. Thus, if you want to revisit a calculation from the past, you don't have to worry about remembering whether you did it on the iPhone or the iPad; it's there in both apps.
Conclusion
Given the iPhone's built-in calculator and the usefulness of Siri, a calculator app needs to do something really special to be worth recommending. But Calcbot is special, and I definitely recommend it, especially on the iPhone. The calculator function is a big improvement over the built-in calculator app, the unit conversions are incredibly useful, and the other features add to the value of the app. This one is worth checking out.
Click here to get Calcbot (free, but $1.99 for Pro version): 
