### RealCalc

(Been using this for a few years and so I'm biased toward it and tend to use it as my benchmark)Pros:

- Has RPN mode
- In RPN mode, number of registers shown is adjustable just by sliding up/down. Max of 4 on my phone.
- binary, hex, octal functions included in free version
- customizable unit conversions and constants

- No random number generator
- Only one RPN style available in free verison, two other options only in paid version
- Fractions capability only in paid version
- 12-digit display is only in the paid version
- Doesn't keep a history of numerical operations, only the numerical results
- Rectangular / polar conversion not available
- one default theme/skin (but it's sufficient with clear and crisp labels on the calculator keys)

### CalcTastic

Pros:- Has RPN mode.
- Has random number generator
- Can generate random numbers (integers) from 0 to x, where x = any integer
- Conversion function (eg., convert from m/s to mph, temp from F to K) has far more units than RealCalc
- The numbers and operations being keyed in (before pressing the equals key) is shown on an upper line with the intermediate and final result shown on the lower line.
- Keeps a history of the operations (eg. multiplication, log, square root) performed, not just the numerical results of those operations
- Stack is accessible even in Algebraic mode
- Has rudimentary statistics package
- Stack doubles as data storage for statistics package (which includes min, max, mean, median, variance, std deviation)
- Can handle complex numbers
- User-selectable theme/skin

- "CalcTastic"?! Seriously?
- Number of lines displayed is fixed. On my phone it's 3 lines of registers in RPN mode and two lines in Algebraic mode
- Binary, hex, octal functions only in paid version
- Rectangular / polar conversion only in paid version
- Fractions capability only in paid version

### Hiper Calculator

Pros:- The number of significant figures makes me giddy: 15 digits on a phone in portrait mode and 32 in landscape mode, with the paid version extending that to 100, and the exponent's from three to nine digits.
- Free version already has fractions capabilities
- Has random number generator
- Keeps a history of the operations (eg. multiplication, log, square root) performed, not just the numerical results of those operations
- The numbers and operations being keyed in (before pressing the equals key) is shown on an upper line with the intermediate and final result shown on the lower line.
- Has an Engineering SI mode! It will, for example, show 10,000 as 10 k, 5.7 million as 5.7 M, 0.000764 as 764 u [symbol for micro]. Quite useful for electronics designers who have to deal with capacitances in picofarads, nanofarads, microfarads, resistances in kilohms and megaohms, currents in microamps and milliamperes. It just isn't natural for them to say, "I need a 2.2 million ohm resistor" or "1 x 10
^{-9}ceramic capacitor." - Binary, hex, octal functions included in free version
- User-selectable theme/skin

- No RPN mode (heartbreaking!)
- For trigonometric functions and logarithms, among others, Hiper uses infix notation, ie., you have to press, for instance the "cos" key before entering the angle value. Am more used to postfix notation for these functions even in non-RPN calculators.
- Rectangular / polar conversion not available