Russian Roulette Probability Puzzle: Should You Spin or Shoot?

The Weekend Russian Roulette Probability Challenge

This week has been all about probability, so it’s only fitting that the weekend puzzle stays on topic.

Imagine you are playing Russian roulette. Two bullets are loaded into two adjacent chambers of a 6-chamber revolver. The cylinder is spun. Someone pulls the trigger — the gun fires, but the person survives. Now it is your turn.

The question: do you spin the cylinder again, or do you shoot without spinning?

Setting Up the Russian Roulette Probability Math

Before jumping to intuition, let’s lay out the structure of the problem.

The revolver has 6 chambers. Two bullets occupy consecutive chambers — let’s call them chambers 1 and 2. The remaining four chambers (3, 4, 5, 6) are empty.

After a random spin, the previous player pulled the trigger and survived. That means one of the four empty chambers fired. The cylinder has now advanced by one position. Your shot will come from whatever chamber is next in line.

Calculating the Odds: Don’t Spin

If you choose not to spin, the outcome depends entirely on which empty chamber was just fired:

• Chamber 3 fired → next up is chamber 4 — safe
• Chamber 4 fired → next up is chamber 5 — safe
• Chamber 5 fired → next up is chamber 6 — safe
• Chamber 6 fired → next up is chamber 1 — bullet

Each of those four empty chambers was equally likely to have been selected by the initial spin. So given that someone survived, you face a bullet in exactly 1 out of 4 scenarios.

Probability of survival without spinning: 3/4 = 75%

Calculating the Odds: Spin Again

If you choose to spin again, the past is irrelevant. You get a completely fresh random draw from all 6 chambers — 4 empty, 2 loaded.

Probability of survival with a fresh spin: 4/6 ≈ 66.7%

The Answer to the Russian Roulette Probability Puzzle

Don’t spin.

Shooting without spinning gives you a 75% chance of survival. Spinning again drops that to roughly 67%. The adjacency of the two bullets is the key — it creates a cluster of “safe sequences” inside the cylinder, and surviving one shot is evidence that you are likely in the middle of such a sequence.

This puzzle is a clean illustration of conditional probability: new information (someone just survived) changes the sample space, and ignoring that information — by spinning again — actually makes you worse off.