Infinite Math: Brain Puzzles

Is π greater than 3.05—can you prove it? From legendary exam problems to classic puzzles, famous math to enjoy as a hobby. Turn spare moments into a brain workout.

That “I solved it!” feeling, all over again. A math app for grown-ups who solve for pleasure—not for any exam. From the wonder of primes and divisors to the crane-and-turtle puzzle, the Monty Hall problem, and even the legendary entrance exams of Japan's top universities— a collection of beautiful problems that make you feel "numbers are fascinating."

■ Made for you if you ・love numbers and logic puzzles ・enjoy giving your mind a workout in spare moments ・want to know not just the answer, but the idea behind it ・are done with exams, but want to rediscover the joy of math

■ Six categories, 55+ problems (more added over time) ・Number Theory & Puzzles … primes, divisors, Fibonacci, perfect numbers, and more ・Classic Problems … crane-and-turtle, Monty Hall, the Königsberg bridges, Pick's theorem, and more ・Elementary Exams … ferris-wheel logic, seesaw puzzles, and other gems ・Junior-High Exams … work, travel, concentration, and counting problems ・High-School Exams … symmetric expressions, probability, Euler's prime-generating formula ・University Exams … legendary stumpers like "Is tan 1° rational?" and "Prove π > 3.05"

■ Highlights ・Daily Problem … one fresh problem to tackle each day ・Sessions … test yourself with five problems at a time ・Explanations worth reading … not just the answer, but the background and the thinking ・Interactive figures … trace the Königsberg bridges or Pick's theorem with your finger ・Progress tracking … solved problems are recorded; aim to clear them all ・19 languages … enjoy these problems in Japanese, English, Chinese, Korean, and more

Answers are simple multiple choice—and some figures come alive at your fingertips. Enjoy the world of numbers on your commute, on a break, or before bed.