It's never too early for maths sequence riddles. Veritasium's Derek Muller offered a selection of strangers a simple sequence of three numbers -- 2, 4, 8 -- and asked them to determine the rule governing the sequence. It's not what you think.
Actually, it is what you think, meaning the problem Muller presents here is meant to challenge how you approach problems. There is a standard way to work out the sequence, but how do people react when the standard way fails?