Best of all the RPN calculator in App Store – Active RPN Calculator Review

I've looked at almost every one of the RPN/HP calculator clones, and for general purpose or light scientific use, Active RPN wins hands down. What I like most about it is the visible stack. I've always used it on my HP 48 and it's immensely useful when you are doing a long series of operations, which is what I typically use calc for.. The UI is well honed, and is pretty simple without throwing up tons of specialized keys that I don't often use. You can even turn off scientific labels to make it more clutter free. It's very well done and well worth the price.
Review by wlai on Active RPN Calculator.