Here's a puzzle that's easy only after you hear the solution: What comes after 3, 4, 6, 8, 12, 14?

3, 4, 6, 8, 12, 14… What comes next?

Or how about 5, 8, 12, 18, 24…?

These two number sequences are real stumpers to figure out (at least for me), but are extremely simple once you know how they work. Neil Sloane, collector of integer sequences since 1965, found these in the puzzle section of a magazine called Eureka. "The first one I could do without cheating," he says, and once he explains it I kick myself for not having had the patience to get it myself. Sometimes drinking three shots of espresso is counter-productive to problem-solving. He then shows us the second sequence above, which is related to the first. See if you can solve them before watching the video!