Math operation in template

Using Django Templates & Frontend
5 
class Airport_Navigation_Aid(models.Model):
    airport =  models.ForeignKey(Airport, on_delete=models.PROTECT, null= True, blank=True)
    Navi_name = models.CharField(max_length=150)
    Ident = models.CharField(max_length=6)
    Name = models.CharField(max_length=100)
    Type = models.CharField(max_length=7, choices=model_choices.NAVI_NAME, default='VOR')
    Frequency = models.IntegerField()
    Elevation = models.IntegerField()

view:

class Airport_Navigation_AidDetailListView(ListView):
    model = Airport_Navigation_Aid
    template_name = 'airports/navilist.html'

def get_queryset(self):
    navigation_list = Airport_Navigation_Aid.objects.all()
    return navigation_list.filter(airport_id = self.kwargs['airport_id'])