I have exactly the same. We will not do anything about this :( Need to fix the ROM.
You need to describe the problem here: https://xiaomi.eu/community/threads/7-4-20.39708/
Now the society each year has a lower IQ. And we have such and no other changes in the calculator. Unfortunately :(
The update was successful. Everything works as it should. (Mi4C)
If
If you learn mathematic in school, you know that 10%=0.1. Percent is the value of the number (10%•90=9). 50+10%=55 - incorrect notation. You should write this: 50+10%•50=55 - good notation