Taken from : http://www.macnn.com/reviews/pcalc-for-ipad.html
PCalc for iPad
April 4th, 2010Themed calculator handles anything you need to convert or compute.
PCalc is a full-featured calculator with RPN, scientific, statistical, and programming modes. It also supports hexadecimal, octal, and binary calculations with themes and a bit of whimsy.
An addition to the TLA Systems family that includes PCalc for Mac OS X and the iPhone, now includes PCalc for the iPad. PCalc is a full-featured calculator with RPN (Reverse Polish Notation), scientific, statistical, and programming modes. It also supports hexadecimal, octal, and binary calculations. There is not a separate iPad version; the latest version 2.0, detects that it is running on an iPad, and reacts accordingly. This means is that if you have an iPhone and an iPad, you can run PCalc on both of them without having to purchase the program twice. It requires the iPad with iPhone OS 3.2 or later, but you can use it with the iPhone and iPod Touch with iPhone OS 3.0 or later.
PCalc supports landscape and portrait orientations, with different layouts for each one.
Horizontal Orientation - Twilight Theme
PCalc is also a themed app and ships with nine different themes. A theme changes the color of the results area, the buttons, and the button bar at the top. In the pictures, the horizontal layout is using the theme named “Twilight,” while the vertical layout below uses the theme “Blue Sun.” My favorite is “Primary Colors.”
Primary Colors Theme
It seems like overkill to use such a powerful application just to add up a series of numbers, but it works great. The large keys are easy to tap. As you would expect from an app that has been on the iPhone and iPod Touch, PCalc shows quite a bit of user interface polish. A flick of the finger to the right lets you undo the last calculation, and a flick back to the left will redo it, so there is never a worry about making a mistake.
Vertical Orientation - Blue Sun Theme
If you need to remember or re-enter a number or two, PCalc supports copy and paste. In fact, it supports multiple clipboards, so you can have several pieces of information waiting to paste. PCalc also keeps a ”paper tape“ of your calculations for you to review. If you have set up Mail on the iPad, you can e-mail the results of a calculation, as well as the contents of the tape.
PCalc with Paper Tape Display
PCalc also has an extensive set of built in conversions. For example, if you want to know how many ounces are in a 2-liter bottle of soda, you enter 2, press the conversion button (the one with the A->B icon), and a list of possible conversions pops up. Choose volume and then liters, and you see how much two liters is in many different measurements of volume, including fluid ounces - both British and American. You can either read the answer from the list 67.628+ for those who care, or tap on it, and that number goes into the calculator for further calculations.
For travelers, PCalc also computes currency conversions. It can convert between about 20 different currencies and can update the rates over a WiFi connection. On a 3G iPad, you can update over a 3G connection as well. I was amused to discover that US $427 equates to approximately 3.9 million Indonesian Rupiah.
iPad with PCalc Currency
For science students, PCalc keeps a list of often used basic constants, such as one standard gravity, the speed of light in a vacuum, Avogadro’s number, the charge on the electron, and PI - those kind of things we all need everyday. All of them are just a couple of taps away in PCalc.
There are little flashes of humor in this otherwise serious app. For example, if you look in the list of universal constants, you will find the “Ultimate Answer” whose value of course, is 42. In fact, it is the 42 button that brings up the list of constants.
Also, if you make a mistake entering a number, just give the iPad a couple shakes; that clears the current entry. Three shakes work the same as the Clear All command.
You can purchase PCalc for iPad in the iTunes store for $9.99. There is also a free version, called PCalc Lite. If you have PCalc Lite, you can upgrade to any of the extra features in PCalc individually, instead of purchasing PCalc, though for $10, I recommend you buy the whole thing rather than upgrade piecemeal.
Edited by Ilene Hoffman, Reviews Editor
Simple to use.
Lots of functionality and conversions.
Bits of whimsy.
Single version runs on iPad/iPhone/iPod Touch–you don't need to buy multiple copies.
A bit pricey compared to other iPad apps.