title: Using a UDF in Excel to update the worksheet
body: <p>Not really a question, but posting this for comments because I don't recall seeing this approach before.  I was responding to a comment on a previous answer, and tried something I'd not attempted before: the result was interesting so I though I'd post it as a stand-alone question, along with my own answer.</p>
  
  <p>There have been many questions here on SO (and many other forums) along the lines of "what's wrong with my user-defined function" where the answer has been "you can't update a worksheet from a UDF" - this restriction outlined here:</p>
  
  <p><a href="http://support.microsoft.com/kb/170787">Description of limitations of custom functions in Excel</a></p>
  
  <p>There are a few methods which have been described to overcome this e.g. see here (<a href="https://sites.google.com/site/e90e50/excel-formula-to-change-the-value-of-another-cell">https://sites.google.com/site/e90e50/excel-formula-to-change-the-value-of-another-cell</a>) but I don't think my exact approach is among them.</p>
  
  <p>See also: <a href="http://spreadsheetpage.com/index.php/oddity/a_user_define_function_cant_change_the_worksheet_oh_yeah/">changing cell comments from a UDF</a></p>