title: Python 'For' Loop Iterate Array
body: <p>I am new to python and I am looking for some help with loop structures, specifically how to use a 'For' loop or alternative loop to solve a problem. I need to figure a discounted price based on the previous days' discounted price in an array so it will iterate through the array an apply the 10% discount. Here is what I have so far:</p>
  
  <pre><code>opnDays = ["mon", "tue", "wed", "thr", "fri"]
  
  price = 10
  
  def discount(array):
      for day in array:
          disPrice = price - (price * .1)
          print(day, disPrice)
  discount(opnDays)
  &gt;&gt;&gt;
  mon 9.0
  tue 9.0
  wed 9.0
  thr 9.0
  fri 9.0
  </code></pre>
  
  <p>I want to get:</p>
  
  <pre><code>&gt;&gt;&gt;
  mon 9.0
  tue 8.1
  wed 7.29
  thr 6.561
  fri 5.9109
  </code></pre>
  
  <p>Any help with how to organize this loop to get a the 10% discount from the previous day would be helpful.
  Thank you</p>