title: Detect if Excel 2013 is installed
body: <p>Excel 2010 can be detected by checking the presence of HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\14.0\Excel\InstallRoot in the registry.</p>
  
  <p>It would seem for Excel 2013 that HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\15.0\Excel\InstallRoot doesn't work.</p>
  
  <p>How can you detect if Excel 2013 is installed?</p>