This Day Is Fractionally Longer

(The professor is writing a math problem on the board.)

Student #1: “Shouldn’t that be one over three, rather than three over one?”

Professor: “Oh, you’re right.”

(The professor erases the numbers, and then writes them up in the same place.)

Class: *laughs*

Student #2: “Um, professor…”

Professor: “Oh dear.” *corrects it very deliberately* “It’s been a long day.”