Brain Game: Prime Time


I try very hard to produce original content for the Brain Game, so it's nice to have the occasional holiday. In fact, our Web editor, Jason, recently suggested that we ask readers to send in their favorite puzzles. That way, other puzzlemakers could earn exposure on, and Kara and I could take our first real break in over a year. Selfishly, we jumped at the suggestion. So if you've got a puzzle that you'd like to share, please send it to me at If your submission makes the cut, I'll give you full credit and will also send you the T-shirt of your choice from the mental_floss store. (That's how badly I need a vacation.)

Students should know this, but here's a quick refresher for those of us who don't: A prime number is one that is evenly divisble only by itself and 1. With that knowledge in mind, try your hand at today's Brain Game:

What is the largest three-digit prime number?

Here is the ANSWER.