In many languages, adjectives have some sort of noun-like inflection. In Latin (Indo-European) and Lingála (Bantu), just off the top of my head, adjectives are marked to agree with the nouns they modify, taking on that noun's gender and number.
In both of those languages, though, there's a curious feature about numbers: small numbers (1-3 in Latin, 1-5 in Lingála) show inflection, while large numbers (anything larger) do not.
Is this a common pattern (or even a "universal"), or just a coincidence that happened to happen in Indo-European and Bantu?