What does 'understand' mean, if not something functional? You mean consciousness? Tough question to answer.

Are you familiar with Daniel Dennett's 'Competence without comprehension' ideas? He points out for instance that even a very simple computer is far better at division and exponentiation than even the smartest human. It does this without any comprehension at all - a pocket calculator is far too simple to have any meaningful understanding of anything, but that has zero impact on its functional usefulness.

Another favourite example of his is evolution by natural selection.

Annoyingly I couldn't find a brief online article on the topic by the man himself.