title: Multiplying three models in django and getting the result in views
body: <p>My model:</p>
  <pre><code>class VisData(models.Model):
  visdata_id = models.AutoField(primary_key=True,blank=True)
  user_name = models.ForeignKey(Customer, null=True, on_delete=models.SET_NULL,blank=True)
  title = models.CharField(max_length=200, null=True,blank=True)
  buy_sell = models.CharField(max_length=1, null=True,blank=True)
  date = models.DateField(auto_now_add=False,null=True,editable=True,blank=True)
  hour = models.TimeField(auto_now=False, auto_now_add=False,null=True,editable=True,blank=True)
  shares_number = models.DecimalField(decimal_places=0,default=0,max_digits=999,null=True,blank=True)
  course = models.DecimalField(decimal_places=2,default=0,max_digits=999,null=True,blank=True)
  fare = models.DecimalField(decimal_places=2,default=0,max_digits=999,null=True,blank=True)
  
  
  def __str__(self):
      return self.title
  </code></pre>
  <p>I want to assign:</p>
  <pre><code>total_value = (shares_number * (course - fare)) and just print it in terminal
  </code></pre>
  <p>My views:</p>
  <pre><code>def summaryPage(request):
  visdata = VisData.objects.all()
  #print(visdata)
  
  context = {}
  return render(request, 'smth/homepage.html', context)
  </code></pre>
  <p>I found some close answers but I couldn't understand the solution nor use them in my code.</p>