Assign a number 1-N for each entry that is returned I need to assign a # 1-N for each entry that is returned -- i.e., 1, 2, 3, 4, ....   (This is for a sort plugin.)

How do I template for that?
If you're in the context of a Twig loop, you have access to the loop variable, which has a number of “magic” properties set.

This allows you to do something like:

{% set posts = craft.entries({ section: 'posts' }).all %}
{% for post in posts %}
  Post #{{ loop.index }} is named: {{ post.title }}&lt;br&gt;
{% endfor %}