Shortcut Key for Converting Value In Cell to Absolute Value

AlexProfile 

There is no built-in shortcut for this. You could create a macro in your personal macro workbook PERSONAL.XLSB and assign a custom keyboard shortcut to the macro.

Sub Convert2Absolute()
    Dim rng As Range
    Dim cel As Range
    Application.ScreenUpdating = False
    On Error Resume Next
    Set rng = Selection.SpecialCells(xlCellTypeConstants, xlNumbers)
    If Not rng Is Nothing Then
        For Each cel In rng
            cel.Value = Abs(cel.Value)
        Next cel
    End If
    Application.ScreenUpdating = True
End Sub

Select a range before running the macro. Cells with formulas and cells that don't contain a number will be ignored by the macro.