Macro That Make Acircle Around Number In A Cell

i want a macro that make acircle around number in acell in excel debending on the nuber that the student given that under 14 has take acircle over is none
like that

this is another example code i fill acell with gray color
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For Each cell In Range("q6:q580")
Select Case cell.Value
Case Is >= 16
cell.Interior.ColorIndex = 2
Case Is < 16
cell.Interior.ColorIndex = 15
End Select
Next cell
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