How to make in ui text when typing in game inside that it iwll not overwrite ?

If I'm typing something in the Inspector inside the ui text it looks like that :



But when I'm clicking the keypad numbers in the game it self the numbers are overwrite each other and it's showing each time only one number :

For example I clicked on 1 and then on 2 but 2 replaced 1 instead adding the 2 near the 1 :



On each key in the keypad I added this script :

Code (csharp):

1.  
2. using System.Collections;
3. using System.Collections.Generic;
4. using System.Text.RegularExpressions;
5. using UnityEngine;
6.  
7. public class SecurityKeypadKeys : MonoBehaviour
8. {
9.     public TextMesh text;
10.  
11.     private void Start()
12.     {
13.        
14.     }
15.  
16.     private void OnMouseDown()
17.     {
18.         string[] digits = Regex.Split(transform.name, @"\D+");
19.         foreach (string value in digits)
20.         {
21.             int number;
22.             if (int.TryParse(value, out number))
23.             {
24.                 text.text = number.ToString();
25.             }
26.         }
27.     }
28. }
29.