title: Excel: adapt column computation to length of data set
body: <p>I.e. the first column has 100 entries and the second also 100, because it uses the corresponding data from the first column</p>
  
  <p>When an entry is added in the first column, the second column should do the corresponding computation on the new entry.</p>
  
  <p>I do not want to write the formula in the whole second column, because it is a very expensive computation. The second column should adapt itself to the length of the first column.</p>