Function HEXOperation(H1, H2, Optional Operator As String = "+") As String
     HEXOperation = ""
     Select Case Operator
     Case "+"
         HEXOperation = Hex(Val("&H" & H1) + Val("&H" & H2))
     Case "-"
         HEXOperation = Hex(Val("&H" & H1) - Val("&H" & H2))
     Case "*"
         HEXOperation = Hex(Val("&H" & H1) * Val("&H" & H2))
     End Select
End Function

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Function SUM_HEX(i, j As String) As String
SUM_HEX = Hex(Val("&H" & i) + Val("&H" & j))
End Function
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Function SUB_HEX(i, j As String) As String
SUB_HEX = Hex(Val("&H" & i) - Val("&H" & j))
End Function
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Function SUM_HEX_RANGE(rng As Range)
For Each cell In rng
a = a + Application.WorksheetFunction.Hex2Dec(cell) + 0
Next
SUM_HEX_RANGE = Application.WorksheetFunction.Dec2Hex(a)
End Function
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Function SumHex(r As Range) As String
Dim cell As Range
Dim iSum As Long

For Each cell In r
If Len(cell.Text) Then iSum = iSum + ("&H" & cell.Value2)
Next cell
SumHex = Hex(iSum)
End Function
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