USAMO Mastery Mock — Objective Edition

NOTE: The real USAMO is a 2‑day, 6‑question proof‑based exam (4.5 hours per day, no multiple choice). This mock adapts core USAMO‑level topics and reasoning into a self‑gradable, multiple‑choice format for independent practice — question count, unit balance, and difficulty curve are matched by design, but the answer format is objective rather than proof‑writing.