title: Excel how to sum rows that share a common attribute
body: <p>In Microsoft Excel, I have many rows of data that each start with and ID value. I want to sum all rows that have the same ID value into one row. How do I do this?</p>
  
  <p>Example:</p>
  
  <pre><code>ID Fig1 Fig2 Fig 3
  1    5    8    2
  1    7    2    6
  2    4    7    8
  2    5    3    0
  </code></pre>
  
  <p>becomes...</p>
  
  <pre><code>ID Fig1 Fig2 Fig 3
  1   12   10    8
  2    9   10    8
  </code></pre>