The next rung up: integer-answer problems (000–999) that call for CRT, recursion, higher Vieta, length-bashing, and expected value. Every problem is original and style-faithful, with verified answers.
Free to start · adaptive placement finds your level · reviews timed so it stays learned.
Every idea is taught with motivation and a worked example before the drills, and an FSRS spaced-repetition engine schedules each review for the moment just before you'd forget it. A short placement check finds what you already know, so you start AIME Problem Solving exactly where it's useful.