Public Class Form1

    Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
        Dim Leftover As Integer
        Leftover = Integer.Parse(txtEnterPennies.Text)
        txtDollars.Text = (Leftover \ 100).ToString
        Leftover = Leftover Mod 100
        txtQuarters.Text = (Leftover \ 25).ToString
        Leftover = Leftover Mod 25
        txtDimes.Text = (Leftover \ 10).ToString
        Leftover = Leftover Mod 10
        txtNickels.Text = (Leftover \ 5).ToString
        Leftover = Leftover Mod 5
        txtPennies.Text = Leftover.ToString
    End Sub

    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        txtEnterPennies.Text = ""
        txtDollars.Text = ""
        txtQuarters.Text = ""
        txtDimes.Text = ""
        txtNickels.Text = ""
        txtPennies.Text = ""
    End Sub

End Class

        If IsNumeric(TextBox1.Text) = True Then

                Insert your code here

        End If

  Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        If e.KeyChar < "0" Or e.KeyChar > "9" Then e.Handled = True

    End Sub

Private Sub txtEnterPennies_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtEnterPennies.TextChanged
If System.Text.RegularExpressions.Regex.IsMatch(Me.txtEnterPennies.Text, "^[-]{0,1}((\d+)|(\d*.\d+))$") = False Then
  Me.ErrorProvider1.SetError(TextBox1, "Numbers only")
  btnCalculate.enabled = False ' Disable button
Else
  btnCalculate.enabled.Tag = True ' Enable button
  Me.ErrorProvider1.Clear()
End If
End Sub

Dim isKey As Boolean = Char.IsDigit(e.KeyChar)

If Not isKey Then
    e.KeyChar = Nothing
End If