Card Numbers by Reenhanced
This is a simple power-up to add card numbers to the front and back of your cards. It is un-obstrusive and puts the numbers in a consistent place.
To activate manually add this url (https://reenhanced.github.io/trello-card-numbers/manifest.json) into the prompt on https://trello.com/power-ups/admin
You get numbers on the card. Uses trello's internal numbering also found on the URL and is searchable.
Send me a pull request, we're likely to accept anything reasonable if it looks good.