Just build 4 of them and chain them together to get 64-bits. (Beyond just being a joke, it is often how things like this get scaled. 1-Bit Adders become 2-Bits

Just build 4 of them and chain them together to get 64-bits. (Beyond just being a joke, it is often how things like this get scaled. 1-Bit Adders become 2-Bits with a Carry Line between, then 3-bits with another Carry Line, and so forth, ad infinitum and beyond. The real joke is the complexity involved in however you "just" chain them together.)