How to add, multiply number variables in a Django template?
django-templates, for-loop, tags
Solution
There is the filter add from the documentation.
I'm pretty sure there are no built-in way to use the other mathematical operations over numbers in Django templates. You can always make your own however. It is not always a good idea to do so.
You want to keep your logic inside the views and keep the rendering inside the templates.
In your case, you should store your counter in a JavaScript variable, and use it in your snippet.
Problem
The JS snippet I created relies on the forloop.counter variable being available within a `{% for key, value in data.items %}..{% endfor %}` tag. Is there a way to use mathematical operators (*, -, +, /) together with the `forloop.counter` variable?