Split 16 digit string into 4 parts and store them in an array in C#

For example, '1111222233334444".

Method 1:

string strNumber = "1111222233334444";

string []strArr = new string[4];

for(int i=0; i < 4; i++)
{
   strArr[i] = strNumber.Substring(i*4, 4);

}

Method 2:
string initial_string = TextBox1.Text;  //read from textbox 

string [] number = new string[4];

number[0] = initial_string.Substring(0,4);
number[1] = initial_string.Substring(4,4);
number[2] = initial_string.Substring(8,4);

number[3] = initial_string.Substring(12,4);