What the AIME Tests
Integer answers –, fifteen problems, three hours. Number theory (CRT, orders, totients, Legendre/Kummer, base representations, digit sums, LTE-lite); algebra (Vieta and Newton sums, symmetric substitutions, functional equations, floor/fractional-part equations, logs and exponentials); counting (recursion, bijections, inclusion–exclusion with structure, expected value, generating functions in easy cases, roots-of-unity filter); geometry (coordinates, complex numbers, mass points, Ceva/Menelaus, power of a point, trig in triangles, 3D solids); sequences (telescoping, periodic recurrences, characteristic equations); trigonometry (product-to-sum, roots of unity products like ).
Gap Fillers
problems are block counts: groups by quotient; " divisible by " gives exactly three per square block. Base- digit conditions are bijections with strings: base-3 numbers with no digit are binary strings read in base .
Digit sums preserve residues mod and shrink fast — is a single digit found by size bounds plus mod . Rational recurrences like are tangent-addition in disguise and have small periods; compute one cycle and reduce the index.
The coefficient of in is Vandermonde (; ). Stars and bars is the coefficient in . Differentiating evaluates — how and both arise.