Number Theory
Primes, divisibility, and modular arithmetic — ancient questions about whole numbers that now secure the internet.
Prof. Gideon Marsh
Professor of Number Theory
Divisibility & Primes
The atoms of arithmetic.
Modular Arithmetic
Clock arithmetic, made rigorous.
GCD, Euclid & the Road to RSA
Ancient math that guards your passwords.
Common questions
Who is "Number Theory" for?
It is written for learners at Undergraduate level (College), and for anyone older who wants a clear refresher on mathematics. Primes, divisibility, and modular arithmetic — ancient questions about whole numbers that now secure the internet. There is no application or entry test — you can start the first lesson straight away.
How long does the course take?
There are 3 lessons totalling 28 minutes of reading and quizzes, laid out over 3 units. You can move at your own pace — progress is saved as you go.
What do I need to know before starting?
No prior coursework is assumed. The course opens with "Divisibility & Primes", covering the division algorithm and infinitude of primes, so the foundations are built in rather than expected.
Is the course free?
Yes. Every course on Monster Class is completely free, with no credit card, trial period or paywall. Creating a free account simply saves your progress, XP and place on the leaderboard across devices.