Q:

How do I multiply values in a query set in django correctly

I want to multiply two values in a queryset how do I achieve this:
This is what I have :
def get_adjustment(self):
        Adjustment.objects.filter(employee_month_id=1,adjustment_type=2)
        .values('exchange_rate','amount').aggregate(Sum('amount', field="exchange_rate*amount") 

A:

You need to use F() objects. 
.values('exchange_rate','amount').aggregate(Sum(F('amount') * F('exchange_rate')))

See the query expressions docs.