Answer by Julia Sobesky:
What number is X?
16 06 68 88 X 98
Just saw this teaser today, and despite my usual knack for puzzlers like this, I was stumped. Apparently, it's quite easy for children to get yet very difficult for adults.
Answer: If you turn it upside-down, the answer is immediate (87), which is likely why children get it quicker because adults try to look for a mathematical pattern in the numbers rather than just orienting their perspective