Refer to this spreadsheet in Zoho. Column D has data in both KB as well as MB. The following macro converts all the values in Column D to a common unit of measure, KB. It uses certain String functions and Mathematical operators to achieve this. This macro is run by selecting the range and then executing the macro.
Sub ConvertToKiloBytes()
For each x in Selection.rows
If Right(x,3) = " MB" Then
Dim mb as double
mb = Left(x,Len(x)-3)
x.value = mb*1024
Else
If Right(x,3) = " KB" Then
x.value = Left(x,Len(x)-3)
End If
End If
Next x
End Sub