title: Cumprod plus addtion on each row
body: <p>I have two vectors</p>
  
  <pre><code>Returns&lt;-c(1.0582529,1.2707149,1.301343,1.1060686,1.0943494)
  Contributions &lt;-c(1000,1250,1500,1750,2000)
  </code></pre>
  
  <p>I want to multiple the returns by the contributions +next row Contribution</p>
  
  <p>so </p>
  
  <pre><code>Returns[1] *Contributions [1] = Result 1
  Returns [2] * Result 1 + Contributions [2] =Results 2
  </code></pre>
  
  <p>etc</p>
  
  <p>where the results would be </p>
  
  <pre><code>Results = c(1058.2529,2933.131353,5769.024454,8316.556852,11289.9178)
  </code></pre>