Mathematics
Clear, organized learning paths that build strong foundations in mathematics and computer science.
A hundred animals, a hundred coins and three prices: Diophantine equations, gcd and congruences to find every solution, or prove that none exists. Twenty problems with click-to-reveal solutions.
ReadA collection with explained solutions: from full cycles to partly full turns, from the GCD to impossible cases. Laboratory with extended Euclid and simulation.
ReadSubstitution, transposition, XOR and RSA: full encryption and decryption examples with an interactive laboratory.
ReadSunzi’s block method, modern congruences, and 30 interactive challenges involving coins, soldiers, calendars, and trick questions.
ReadFajtlowicz’s conjecture, two ways to generate primes from 3 and 5, and a laboratory that also accepts a new starting pair.
ReadFrom clocks to enormous powers: an intuitive guide to congruences with 25 problems and an interactive laboratory.
ReadAverbach and Chein’s method: interpret integer coefficients as fills and empties, construct the pours and follow them in a laboratory with two animated bars.
ReadThe exact solution to a sequence-position problem in which every natural number n appears exactly n times.
ReadDivisibility, the sieve of Eratosthenes and regularities that help explore primes.
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Lines, exponentials, powers and parabolas: identify the question, calculate coefficients and examine data in a visual laboratory.
ReadTwo problems about starting at the end: prepare a deck and construct winning seats in Josephus. With a laboratory, a birthday application and a chosen pair.
ReadBisection, Newton, Taylor and numerical integration explained with examples. Two interactive laboratories show steps and errors.
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