title: assigning a value based on another column in Excel
body: <p>I am trying to find a quick way to assign a value for a column depending on the value of another.I want to increase the value of column A by one each time the value of column B changes.</p>
  
  <pre><code>Column A    Column B
  
  1           (520)998-7765
  1           (520)998-7765
  1           (520)998-7765
  2           (450)877-4563
  2           (450)877-4563
  2           (450)877-4563
  2           (450)877-4563
  3           (650)989-7654
  3           (650)989-7654
  3           (650)989-7654
  ....        ....
  </code></pre>
  
  <p>I need to know if there is a formula that I can use to sort through 27,000 lines of data rather than assigning them one by one.</p>
  
  <p>I am using a phone number as a unique identifier and I want the ID# to increase by one every time the phone number changes.
  Please Help!!
  <img src="https://i.stack.imgur.com/jAjim.png" alt="here is the image"></p>