Use listView
instead of listBox
On form load add two column:
private void Form1_Load(object sender, EventArgs e)
{
listView1.View = View.Details;
listView1.Columns.Add("Number", 50, HorizontalAlignment.Left);
listView1.Columns.Add("Bet", 50, HorizontalAlignment.Left);
}
And when you creating a new bet just get the values and save to the listView
ListViewItem item = new ListViewItem();
item.Text = number;
item.SubItems.Add(bet.ToString());
listView1.Items.Add(item);