I upgraded from build 11102 to build 14251 than cleaned the system ( including Windows.old files ) using CCleaner.
This caused the built in calculator to not function. After trying all solutions found on the web, I used windows file cleaner per instructions at ( http://www.tenforums.com/tutorials/2066-windows-old-folder-delete-windows-10-a.html ).
The calculator is working correctly now. When opening CCleaner to uncheck this option the item no longer existed, I assume this is normal.
This problem did not exist on previous builds.
Richard