Numerology is a very common direction to take with the Tarot. You can approach this from a very general to a very specific viewpoint.
Specifically, each card has its own number. This applies to both the major and minor arcana. Each of these numbers have a numerological meaning that can also apply to the meaning of the card.
More generally, look at the amount of cards in the deck (78), the amount of arcana (2), and the amount of suites (4). The amount of cards in the two arcana (major =22; minor= 56) can also provide greater depth of meaning for your Tarot experience.
Here are some helpful web sites for your investigations: