I have found the quintessential you-won't-find-it-if-you-don't-know-it question:
Question: "What is the next element of this sequence: 2,3,4"
Answer:
82000
Short explanation:
2 is the minimum integer $>1$ that can be written in base 2 only using digits 0 and 1.
3 is the minimum integer $>1$ that can be written in bases 2,3 only using digits 0 and 1.
4 is the minimum integer $>1$ that can be written in bases 2,3,4 only using digits 0 and 1.
82000 is the minimum integer $>1$ that can be written in bases 2,3,4,5 only using digits 0 and 1.
Long explanation & source:
Now my question is: How can I articulate a small answer well? Notice how the current "Short explanation" is very repetitive. It is (kinda) easy to grasp, sure, but I'd rather have an opening "condensed" version first, and then explain further.