title: Regular expression number extraction from string
body: <p>I'm looking to see if the following string(s) match the number 1 in them</p>
  
  <p>23_13_15_145_34_1_135</p>
  
  <p>23_13_15_145_34_1</p>
  
  <p>1_23_13_15_145_3</p>
  
  <p>I only want to match it exactly so the first example must not include the 13, 15 or 145, just the 1.</p>
  
  <p>Same with the start and end examples with the 1 at the start and end of the string.</p>