Develop a function that can set a prefix on every number

static void Main()
        {
            int input = 5555;
            string output = PrefixWithCharacter(input, '0', 10);

            Console.WriteLine(output);  // outputs 0000005555
            Console.ReadLine();
        }

        static string PrefixWithCharacter(int input, char value, int length)
        {
            StringBuilder format = new StringBuilder();

            for (int i = 1; i <= length; i++ )
            {
                format.Append(value);
            }

            return input.ToString(format.ToString());
        }

2870 and 0028790 are the same thing.. and probably it can't be done as integer... i don't know...

but this maybe help you

textBox1.Text= textBox1.Text.PadLeft(10, '0');

 

the return value is String not number.. and if you try to convert to number it become 2870 again...

but it maybe is what you are looking for