I can confirm that a Data Type Column cannot be used in a Formula. But there is an easy workaround using Workflows in SharePoint Designer 2010/2013 without any coding required

• Create an additional Column in your list (DataTypeColumn01) as type Single Line Text
• In SharePoint Designer, open the List from the specific website and click New on the Worflows tab

• Give the Workflow an appropriate name and select the Platform; either SharePoint 2010 /2013 Workflow
• From Workflow Tab select Action – List Actions – Set Field in Current Item
• Set DataTypeColumn01 to CurrentItem:DataTypeColumn
• Use the lookup button next to the Action to achieve this

• Save the Workflow
• Enable the Start Options for the Workflow as per your requirement

• Publish the Workflow
• You can now use the DataTypeColumn01 Column with any SharePoint Formula