Binary Tree Quiz

1-min mobile game

**What number is hiding behind the "?"**

Somewhere in this binary tree, one node is hiding its number behind a "?". Pick a number and hit Answer — that's the whole game, and it only takes about a minute.

Guessing wrong is totally fine — the wrong number joins the tree right where it belongs, giving you a fresh clue. Use the binary tree rule (smaller goes left, bigger goes right) to narrow things down and try to land the answer in as few guesses as possible.

**How to play**

- Pick a number with the ◀▶ buttons, then tap **Answer**

- Wrong guesses get added to the tree — narrowing your remaining candidates

- 5 questions total, with the number range growing each round

- Nodes wobble a little if you grab and drag them — just for fun

**Features**

- A quiz that quietly teaches you how binary search works

- Each round takes 30 seconds to a minute — perfect for a quick break

- Fully playable in Japanese and English (switch anytime from the button)

- One-touch controls on both mobile and desktop

**Goal**

Guess all 5 numbers on the first try for a "Perfect" rating — the fewer total guesses, the better your result screen. See how close to a flawless run you can get.