Multiple choice general knowledge math & puzzles

You have an unlimited number of coins with a diameter d and you stack them. The goal is to let the topmost coin stick out as far as possible. The Question: What is the maximal distance between the center of the topmost coin and the center of the lowermost coin? Take the thickness of a coin as t.

  1. d

  2. Between d and 3d/2

  3. Depends on d and t

  4. Infinity

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

By carefully stacking each coin at the edge of the previous one, the overhang can grow without bound (harmonic series diverges). With unlimited coins, the top coin can be made to stick out arbitrarily far from the bottom coin's center. Thickness affects how many coins needed but not the theoretical maximum.