Right-click on the sheetname at the bottom of the screen and
paste the following code
Private Sub Worksheet_Change(ByVal Target As Range)
'Do nothing if more than one cell is changed or content deleted
If Target.Cells.Count > 1 Or IsEmpty(Target) Then Exit Sub
'Check whether the cell value is 0.5
If Target.Value = 0.5 Then
'Insert a row below the cell with value 0.5
Target.Offset(1, 0).EntireRow.Insert
End If
End Sub
Now a row will be inserted below the cell if you enter 0.5 in any cell
If you want to insert only a cell then use
Private Sub Worksheet_Change(ByVal Target As Range)
'Do nothing if more than one cell is changed or content deleted
If Target.Cells.Count > 1 Or IsEmpty(Target) Then Exit Sub
'Check whether the cell value is 0.5
If Target.Value = 0.5 Then
'Insert a row below the cell with value 0.5
Target.Offset(1, 0).Insert Shift:=xlDown
End If
End Sub