Reverse Polish Notation in the Calculator

For RPN support you will need to go third party.

As the developer I am biased but I suggest taking a look at Perpenso Calc. It is five calculators in one: scientific, statistics, business, hex and bill/tip. With its support for RPN, fractions, complex numbers and many other features it is comparable to traditional handheld calculators. iPad specific functionality includes customizable display lines.

A related iPhone app, Perpenso Calc 4, is a lite app and is upgradable to full via In-App Purchase. RPN is only supported in full mode but lite mode will give you an idea of what the calculator can do in its scientific mode which includes fractions and complex numbers.

http://www.perpenso.com/calc/calc3.html

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No, but there are numerous calculator apps in the App Store that provide that, including several that emulate HP calculators.

I may receive some form of compensation, financial or otherwise, from my recommendation or link.

As long as that's tattooed on your forehead, you aren't violating forum rules.