title: Excel - If confition then sum dynamic range/label
body: <p>Excel Content</p>
  
  <pre><code>     A      B       C         D     
  01    Label Value   Result  Expect result
  02    Car       2       4       10
  03    Car       2       4       10
  04    Car       2       4       10
  05    Car       2       4       10
  06    Car       2       2       10
  07    Van       1       2       5
  08    Van       1       2       5
  09    Van       1       2       5
  10    Van       1       2       5
  11    Van       1       1       5
  12    Boat      3       6       15
  13    Boat      3       6       15
  14    Boat      3       6       15
  15    Boat      3       6       15
  16    Boat      3       3       15
  </code></pre>
  
  <blockquote>
    <p>i try to use if condition and sum but not work...
    e.g for C1 <code>=if(A2=A3,sum(B2:B3),B2)</code>
    e.g for C2<code>=if(A3=A4,sum(B3:B4),B3)</code> </p>
  </blockquote>
  
  <ol>
  <li>I have been sorted the data by label</li>
  <li>How can i count the total of value if next label is not equal ?</li>
  </ol>