Maybe something like this ...


Option Explicit
Sub CheckItemNumbersForJack()
    Dim cel As Range, rng As Range, tmp
    Set rng = Sheets("Compare").Range("E12", Sheets("Compare").Range("E65536").End(xlUp))
    With Sheets("Numbers increased by Star")
        For Each cel In rng
            Set tmp = .Range("A:A").Find(cel.Value, _
                lookat:=xlWhole, MatchCase:=True)
            If Not tmp Is Nothing Then
                cel.Interior.ColorIndex = 4
                tmp.Interior.ColorIndex = 4
            End If
        Next cel
    End With
End Sub