title: Regex that accepts only numbers (0-9) and NO white spaces
body: <p>I need a regex that will accept only digits from 0-9 and no white spaces. Example:</p>
  
  <p>35 62 30 36 63 63 61 63 39 65 34 66 64 33 34 62 66 66 61 63 34 38 39 38 </p>
  
  <p>And i want this:
  356230366363616339653466643334626666616334383938</p>
  
  <p>Is this possible? 
  Thanks in advance!</p>