title: Power BI Cummulative Subtraction
body: <p>I have a calculated table in which I get the percentage by dividing actual cost by total cost and then multiplying by 100. </p>
  
  <p>I show this value on weekly basis like that:</p>
  
  <pre><code>Week 1 | Week 2 | Week 3 | Week 4
  -------+--------+--------+-------
      70 |     80 |     60 |     90 
  </code></pre>
  
  <p>but I want to change it like this:</p>
  
  <pre><code>Week 1 | Week 2 | Week 3 | Week 4
  -------+--------+--------+-------
      70 |     80 |     60 |     90 
         |     10 |    -20 |     30
  </code></pre>
  
  <p>Currently I am using this formula:</p>
  
  <pre><code>Percentage_weekly_confirmation_rate = DIVIDE([Accepted PO Cost], [Total PO Cost])
  </code></pre>
  
  <p><code>Accepted PO Cost</code> and <code>Total PO Cost</code> are both calculated values.</p>
  
  <p>What should I do to achieve the desired result?</p>