TemplateSyntaxError at / Could not parse the remainder: ' + 1' from 'forloop.counter0 + 1'

I created dynamic slider using bootstrap. I want to show number indicator for slider, so I added one to variable in forloop. But I m getting the following error "TemplateSyntaxError at / Could not parse the remainder: ' + 1' from 'forloop.counter0 + 1'". 

Custom Filter Example: 

This is just an example for custom filter.

Resolve with custom filter:

In django, we cannot perform arithmetic operations using template tags. To achieve this I created a custom template filter.

Create a folder named "templatetags" in django app and create a empty file named "__init__.py" inside the folder. Then, 

Create a template filter in django app, "Custom_filters.py". 

Copy and pasted below code:

# custom_filters.py
from django import template

register = template.Library()

@register.filter
def add_one(value):
    return value + 1

In Html Template, load the custom filter at the top of the template.

Use the custom filter to add 1 to the 'forloop.counter'

{% for item in sliders %}
  <li data-bs-target="#myCarousel" data-bs-slide-to="{{ forloop.counter0|add_one }}" {% if forloop.first %} class="active" aria-current="true" {% endif %}  aria-label="Slide {{ forloop.counter0|add_one }}">{{ forloop.counter0|add_one }}</li> 
{% endfor %}

OUTPUT:

Video Guide