how to import celery tasks in django views

I am learning celery with django. I am trying to create a simple addition project with django and celery. I created a simple webapp with django. in the index.html template, I have a form with 2 input fields. The first input field takes the x value (the first number for addition). The second input field takes y value (the second number for addition). When the form is submitted, I want the celery task to run. The django project name is core and the app name is mainapp

The celery task is as follows

mainapp/tasks.py

from celery import Celery
from celery.schedules import crontab
from celery import shared_task

@shared_task
def add_num(x, y):
    return x+y

core/celery.py

from __future__ import absolute_import, unicode_literals
import os
from celery import Celery

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'core.settings')

app = Celery('core')
app.conf.timezone = 'UTC'
app.config_from_object("django.conf:settings", namespace="CELERY")
app.autodiscover_tasks()

mainapp/views.py

from django.shortcuts import render
from . import tasks

# Create your views here.
def index(request):
    if request.method == 'POST':
        x = request.POST['x']
        y = request.POST['y']

        print(x, y)

        add_num.delay(x, y)

        return render(request, 'index.html')

    return render(request, 'index.html')

I have rabbitmq running in the background with the following command

brew services start rabbitmq

celery is running in a separate terminal window with the following command

celery -A core worker -B -l INFO

When I submit the form I get the following error.

NameError: name 'add_num' is not defined

I guess I am not importing the tasks into views.py properly.