Calculator app issue on my iPhone

I have been using iPhone calculator daily for years with no problems and now some of the most simple of calculations aren’t working the way they should. I work mainly with the percentages and instead of providing me with what a percentage of a a number should be it just gives me the number after the percentage is added or deducted. I’m not sure if I am explaining this correctly. I don’t know why a perfectly functioning calculator had to lose some very basic functions. I’m really disappointed with this update. It is not an improvement. I’m seeking out a new calculator app.

[Re-Titled by Moderator]