Quantitative & Math — number sense over calculation.

8 puzzles across five archetypes that trade heavy arithmetic for number sense: mental-math shortcuts, equation-balance logic, prime and Fibonacci patterns, probability intuition, and cryptarithmetic (the classic "letters stand for digits" puzzle, as in SEND + MORE = MONEY).

Built for intuition, not long division

None of these puzzles need a calculator — they need you to notice structure. Math Hacks trains the arithmetic shortcuts mental-math competitors actually use (squaring numbers near a round base, for instance), Probability Visualizer builds intuition for outcomes that feel wrong until you enumerate them, and Crypto-Arithmetic is pure constraint propagation: each letter is a fixed unknown digit, and the puzzle is solved by elimination, the same logic underlying Sudoku.