HP12C Do NOT PURCHASE!!! A waste of Money – HP 12C Financial Calculator Review

I have used an HP12C for years but when I purchased the HP12C app. and tried to use it, ONLY 1/2 of the Calculator Screen shows so you certainly can NOT figure mortgage payments nor any of the other calculators you want to accomplish. I would really appreciate it if someone can tell me what I am doing wrong____ when you first see the app, it shows the whole screen but when you go to use it, only 1/2 of the screen shows for you to use____and for “this” I had to pay almost $20 for this useless app!!! ???
Review by Realtor in SC on HP 12C Financial Calculator.