Problem:  I inserted a column and entered some formula into it.  But after pressing enter, it was displaying the formula itself instead of its calculated values. Solution:

• Highlight the column (in my case), row or cells; wherever the problem is.
• Right click on selection.
• Select ‘Format Cells…‘ option.
• Click on ‘Number‘ tab, if not already on it.
• Click on ‘General‘ option under ‘Category‘.
• Click OK to close the dialog box.
• Recalculate the sheet/cells.