Django ページネーションについて教えていただきたいです

Python Djangoという参考書で勉強していたのですが
４−３ページネーションの「ページの移動はどうするの？」で躓いてます。
firstはちゃんと動くのですが、prev,next,lastがどうしてもPage not foundになってしまいます。
何方か教えてくれませんか？
ソースはこんな感じです
初投稿なのでうまく使えてないと思います。すみません
django_app/hello/url.py
from django.urls import path
from . import views

urlpatterns=[
path('',views.index,name='index'),
path('int:num',views.index,name='index'),
path('create',views.create,name='create'),
path('edit/int:num',views.edit,name='edit'),
path('delete/int:num',views.delete,name='delete'),
path('find',views.find,name='find'),
path('check',views.check,name='check'),
]

django_app/hello/views.py
from django.shortcuts import render
from django.http import HttpResponse
from django.shortcuts import redirect
from .models import Friend
from .forms import FriendForm
from .forms import FindForm
from django.db.models import Q
from django.db.models import Count,Sum,Avg,Min,Max
from .forms import CheckForm
from django.core.paginator import Paginator

def index(request,num=1):
data = Friend.objects.all()
page = Paginator(data,3)
params = {
'title': 'Hello',
'message':'',
'data': page.get_page(num),
}
return render(request,'hello/index.html',params)

#create model
def create(request):
if (request.method == 'POST'):
obj = Friend()
friend = FriendForm(request.POST,instance=obj)
friend.save()
return redirect(to='/hello')
params = {
'title' : 'Hello',
'form' : FriendForm(),
}
return render(request,'hello/create.html',params)
def edit(request,num):
obj = Friend.objects.get(id=num)
if (request.method == 'POST'):
friend = FriendForm(request.POST,instance=obj)
friend.save()
return redirect(to='/hello')
params={
'title' : 'Hello',
'id' : num,
'form' : FriendForm(instance=obj),
}
return render(request,'hello/edit.html',params)
def delete(request,num):
friend = Friend.objects.get(id=num)
if (request.method == 'POST'):
friend.delete()
return redirect(to='/hello')
params = {
'title' : 'Hello',
'id' : num,
'obj' : friend,
}
return render(request,'hello/delete.html',params)

def find(request):
if (request.method == 'POST'):
msg = request.POST['find']
form = FindForm(request.POST)
sql = 'select * from hello_friend'
if (msg != ''):
sql += ' where ' + msg
data = Friend.objects.raw(sql)
msg = sql
else:
msg = 'search words...'
form = FindForm()
data =Friend.objects.all()
params = {
'title' : 'Hello',
'message' : msg,
'form' :form,
'data' :data,
}
return render(request,'hello/find.html',params)
def check(request):
params={
'title' : 'Hello',
'message' : 'check validation.',
'form' : CheckForm(),
}
if (request.method == 'POST'):
obj = Friend()
form = FriendForm(request.POST,instance=obj)
params['form'] = form
if (form.is_valid()):
params['message'] = 'OK!'
else:
params['message'] = 'no good.'
return render(request,'hello/check.html',params)

django_app/hello/template/hello/index.html
{% load static %}

{{title}}

{{title}}

{{message|safe}}

{% for item in data %} {% endfor %}

id	name	age	mail	birthday
{{item.id}}	{{item.name}}	{{item.age}}	{{item.mail}}	{{item.birthday}}

{% if data.has_previous %} «first «prev {% endif %} [{{data.number}}/{{data.paginator.num_pages}}] {% if data.has_next %} next» last» {% endif %}