Mental Floss

Brain Game: Pop Quiz


If you haven't yet turned off your thinking organ for the summer, try today's Brain Game. We've offered a few number-series puzzles before, but this one may require a little lateral thinking (and, for some of you, a conversation with someone more over-the-hill).

What's the final number in this sequence? 6.5, 8, 10, 12, 16, ...

Click here for the answer.

Answer: 20. The numbers represent increasingly large sizes of individual-serving Coca-Cola bottles, from the earliest and smallest (6.5. oz glass) to the newest and largest (20 oz. plastic). Larger bottles contain more than one serving.