title: How to add selected numbers in a list in Python
body: <p>I have a list of numbers , and I want to add up the numbers, but I don't want to add all the numbers from the list, just the selected numbers, like the first three.</p>
  
  <pre><code>list = [2, 3, 7, 11, 15, 21]
  for i in list:
     sum += i
  </code></pre>
  
  <p>My code obviously adds up all the numbers from the list. I've tried changing the for loop to in range(0,4) but that just added together numbers 0, 1, 2, 3 and not the numbers from my list. So how can I modify my code to add up the first three numbers from my list.</p>