As a last resort, you can try deleting Windows Calculator completely and then reinstalling
Sometimes, deregistering the application (uninstalling and installing) doesn’t completely remove the installation files. So when you install the Windows Calculator again, you think that you got new files from the Windows Store, but in reality, your OS is reinstalling the files that were already present on your PC.
We can use a trick where we activate an administrator account, grant you access, and then delete the installation files so you can download them again from the Windows Store.
First, we will enable the Administrator account. Run command prompt as an administrator and enter “net user Administrator /active:yes”
Now if you open your start menu and click on your profile icon, you will see a new administrator account present.
Open the account and navigate to Local disk C. Open the folder of “Program Files” and locate “WindowsApps”. If you can’t find WindowsApps, click on View present at the top of your file explorer window and check the box which says “Show hidden items”.
Now go to its Properties and grant full access to your account.
Now switch back to your account and navigate to Drive C > Program Files > WindowsApps
Now, look for every folder which says “WindowsCalculator”. For each of these folders, you need to go to their properties and change the ownership from SYSTEM to your user account. Then you can grant full access to your account.
Now delete all the folder which contains the keyword “WindowsCalculator”. You can now reinstall the calculator from the Windows Store.
If you do not use your calculator often and you do not want to go thru all that work there is another option for you. Browsers like Chrome and Firefox will calculate for you. Just type the math into the address bar and you will get your answer. example (2*5)*10