public static void Main()
Console.WriteLine("1234567 = " + formatSku("123"));
Console.WriteLine("1234567A = " + formatSku("123A"));
Console.WriteLine("12Z3A = " + formatSku("12Z3A"));
public static string formatSku(string sku) {
string formattedSku = "";
if(Int32.TryParse(sku, out numericSku)) {
formattedSku = numericSku.ToString("00000000");
string mainSku = sku.Substring(0, sku.Length - 1);
if(Int32.TryParse(mainSku, out numericSku)) {
formattedSku = numericSku.ToString("00000000") + sku.Substring(sku.Length - 1, 1);