Mine just went to hell in the last few days, not sure why or how the updates work but the last one I was aware of was a couple of weeks ago, and it didn't affect my calculator til now.
It is worthless to me now and I use it every day. Most of the time I had the phone vertical as I was just doing basic math functions. But sometimes I need a memory so I flipped it and it was right there. Just tonight I flipped it and had to turn the "Scientific" function on. So I did with the 3 bars in the upper left corner where there were several options, and now it's on both views and I can't get rid of it. When I hit the 3 bars all it shows now is history.
So they've gone from using round wheels to inventing and forcing on me triangular wheels, apparently.
I just tried out the HP app mentioned above, it isn't much better. Any other ideas, or do I have to dig out my old calculator from the desk drawer that I haven't used in years. Assuming I didn't throw it out.