To do summation of multiplication of two fields with Python Django aggregation, we can call the aggergrate method.
For instance, we write
from django.db.models import F
Task.objects.aggregate(total=Sum(F('progress') * F('estimated_days')))['total']
to call aggregate to use Sum and F to sum up the progress multiplied by the estimated_days values.
And then we get the total value from the aggregation to return the value.