Summary: I had one in college in the 1980's. I loved it. However, the HP quality that I expected was not there. The keys are mushier. Still, it works fine. I just don't have the confidence that I entered numbers correctly, without checking the display.
Summary: Great calculator for less than $20 at iTunes store. Get virtual calculator for use on phone and tablet and save lots of money. Have had physical HP 12C calculators for over 25 years (and they all still work).
Summary: I am a true fan of the HP 15C (the original). However, when I tried to calculate sin(45), it gives me the answer as if I were calculating it in radians, not degrees. I tried to convert to degrees, the display indicates I am not in radians, but the answer is still 0.8509 instead of 0.7071.
HP-15C is a Great Calculator, solidly built and easy to use in your hands.
3 August 2014
Summary: This is the ultimate 10 series calculator from HP. It is so good and popular that HP did a special edition re-manufacture years after it went out of production. The original HP 15C is heavier, solidly constructed and lasts.
It is like a "Linus blanket" (Charlie Brown reference)
John P., Amazon
19 June 2014
Summary: I am lucky to have hidden my original 1980's HP 15C ,from the ex wife on a cleaning out the house weekend whim. I recently pulled it off the bench and put it back into the game. I decide to go back to academia at a latter point in my life. I am the oldest in the class.