What did the 0 say to the 8?

This joke plays on the visual similarity between the numbers “0” and “8.” The number 0 is round, and when you add a belt (or cinch the middle), it resembles the number 8, which looks like a 0 with a narrower center, as if it were being squeezed by a belt. The humor arises from personifying the numbers, imagining them having a conversation where “0” compliments “8” on its “nice belt,” which is actually just the constricted middle part of the figure 8.