TL;DR
Invariant Arguments: The Parity Trick: A canonical quantitative trading interview question at intermediate difficulty. Commonly asked at Jane Street, SIG, Optiver, IMC, Citadel.
By Valenke Exam Prep Team·Last updated 2026-06-01
intermediateClever Arguments
Invariant Arguments: The Parity Trick
Asked at: Jane Street, SIG, Optiver, IMC, Citadel
Problem
On a board, the numbers are written. In each move, you pick any two numbers and , erase them, and write in their place. After 24 moves, one number remains.
(a) Can the final number be 0?
(b) Can the final number be 1?
(c) What are all possible final numbers?
Related concepts
Ready to practice for the Valenke Finance Exam?
Adaptive practice powered by Item Response Theory targets your weak areas. Start with 3 free sessions.
Start free practice →