VB 숫자만 가져오기

Function numOnly(str As String) As Variant
    Dim strTemp As String
    Dim intNum As Integer
   
    For intNum = 1 To Len(str)
        If IsNumeric(Mid(str, intNum, 1)) Then
            strTemp = strTemp & Mid(str, intNum, 1)
        End If
    Next intNum
    numOnly = strTemp
End Function