iCalculator

It is working for me with Monterey 12.2:

If it's not working for you boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

That's not calculating a percentage. Try 100 x 10% and it will give you .10 which is wrong. 10% of 100 is 10

I get 10. When you hit %, you should see 0.1 because 10% is 0.1. When you finish the calculation, it should give you 10.

What do you mean? If I enter 9 and then click on % 0.09 is displayed.