No one sees 1+1 as 3. They see it as 2.
I don't think that statement is correct, let's just say for example dyslexia, people that literally see letters and numbers backwards. Or schizophrenics, who literally see a different reality from the consensus entirely. The only reason we say they see things the wrong way is because communally we have decided that the majority ideas and perceptions are correct and logical. Everything is relative. For your math thing I have kind of a weird example. Technically 1 decided by two = .5, but my corals reproduce by having one head split into two or three. The three is really interesting because I literally have an animal growing that can take one of itself and divide to produce 3x itself. It doesn't sacrifice it's size when it splits, so even though it is dividing, it is essentially multiplying exponentially at the same time.