If you click on the calculator in Windows 10 and receive the error "You'll need a new app to open this calculator", follow these steps to resolve!
Open registry editor as Admin and navigate to the following regkey:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Appx\AppxAllUserStore\
Perform a backup of the regkey.
Delete all the UserSid (S-1-X) keys and then restart the computer.