Optimal Stopping with a Ten-Sided Die and a Reset

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Quick Overview

Derive optimal stopping thresholds for a fair ten-sided accumulation game, then account for the continuation value of a one-time zero reset.

Optimal Stopping with a Ten-Sided Die and a Reset

Role: Quantitative Researcher

Category: Statistics & Math

Difficulty: medium

Interview Round: Technical Screen

Roll a fair ten-sided die labeled 0 through 9. A positive roll adds its value to your running total. A zero ends the game and loses the entire total. After each non-ending roll, you may stop and receive your current total. What strategy maximizes expected winnings? Now change the rule: the first zero resets your total to zero but allows you to continue; the second zero ends the game with no winnings. How does the optimal strategy change? ### Constraints & Assumptions Rolls are independent, there is no cost per roll or finite horizon, and the objective is expected cash payout. In the variant, a reset does not bank any previous total. The state must include whether the first zero has already occurred. ### Clarifying Questions Can you stop after a reset? Does the first zero reset or preserve the total? Is the objective expected value rather than probability of exceeding a target? ### What a Strong Answer Covers A stopping-versus-continuing comparison, a proof of the threshold policy, and a state-aware treatment of the extra reset. Define any constant needed for the second threshold precisely. ### Follow-up Questions Why is comparing the next roll's average increment alone insufficient after a reset option is introduced? What happens at an exact indifference threshold? How would a per-roll cost alter the Bellman equation?

Overview: Derive optimal stopping thresholds for a fair ten-sided accumulation game, then account for the continuation value of a one-time zero reset.

Read the full Quantitative Researcher interview experience this question came from

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Jun 2, 2026
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Roll a fair ten-sided die labeled 0 through 9. A positive roll adds its value to your running total. A zero ends the game and loses the entire total. After each non-ending roll, you may stop and receive your current total. What strategy maximizes expected winnings?

Now change the rule: the first zero resets your total to zero but allows you to continue; the second zero ends the game with no winnings. How does the optimal strategy change?

Constraints & Assumptions

Rolls are independent, there is no cost per roll or finite horizon, and the objective is expected cash payout. In the variant, a reset does not bank any previous total. The state must include whether the first zero has already occurred.

Clarifying Questions Guidance

Can you stop after a reset? Does the first zero reset or preserve the total? Is the objective expected value rather than probability of exceeding a target?

What a Strong Answer Covers Guidance

A stopping-versus-continuing comparison, a proof of the threshold policy, and a state-aware treatment of the extra reset. Define any constant needed for the second threshold precisely.

Follow-up Questions Guidance

Why is comparing the next roll's average increment alone insufficient after a reset option is introduced? What happens at an exact indifference threshold? How would a per-roll cost alter the Bellman equation?

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