title: How to filter all non-numeric characters ,and digits to make from string to numbers
body: <p>I want to activate a function by following these steps:</p>
  
  <p>1.First filter out all non-numeric characters.</p>
  
  <p>2.Calculate any linear function on these numbers.</p>
  
  <p>3.Calculate the product of each results and return an answer.</p>
  
  <p>ex:</p>
  
  <pre><code>&gt;&gt;print(digit_com_mul("8?97D4b"))
  
     36
  </code></pre>
  
  <p>This is the function I tried to perform but I do not understand how after the filter to turn the string into numbers</p>
  
  <pre><code>def digit_complete_mul(data):
       return reduce(lambda x,y:x*y,map(lambda x: 10-x,int(filter(lambda x:x.isdigit(),data))))
  </code></pre>