title: conditional concatenation of cells based on cell values
body: <p>I have a table with data spans from C24:H28.  There are headers for each column in row 23 (Note that the data is not formatted as a table, just a spreadsheet).  In cell A1, I want to display the header names for any column containing data less than a value of 100 separated by a comma.  I know EXCEL's <code>CONCATENATE</code> function is what I am looking for here, but I am not sure how to create the formula to conditionally concatenate based on the contents of the columns.</p>
  
  <p>A truncated example is below:</p>
  
  <pre><code>Tom     Joe     Bob   ...
  125     245     325  ...
  60      600     164  ...
  305     20      410  ...
  </code></pre>
  
  <p>I would want cell A1 to read <code>Tom, Joe</code></p>
  
  <p>I am hoping to avoid Macros if possible.</p>