Funny story

My professor told me this story about how math is all about effectively communicating ideas.

He was at a conference and someone just finished giving a long, complex lecture on some cutting edge math across several chalkboards, and he opened up the floor for questions. A professor raises his hand and asks, "How do you get 4?" pointing to a spot on the board. The lecturer looks over everything he wrote before that, trying to find where the misunderstanding was. He finally says "Oh, 3 plus 1!" The professor in the audience flips through the several pages of notes he had written and eventually says, "Oh yes yes yes, right."