These settings will retain the Calculator's windows position and history.
I did not run it as a DirectFlex...but it could be.  I was just keeping it simple.

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[IncludeRegistryTrees]
HKCU\SOFTWARE\Classes\calculator
HKCU\SOFTWARE\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppContainer\Storage\microsoft.windowscalculator_8wekyb3d8bbwe
HKCU\SOFTWARE\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\AppModel\SystemAppData\Microsoft.WindowsCalculator_8wekyb3d8bbwe

[IncludeFolderTrees]
<LocalAppData>\Packages\Microsoft.WindowsCalculator_8wekyb3d8bbwe