Wolfram MathWorld contains more than 13,000 illustrated mathematics entries with interactive examples.
Cut The Knot
Cut the Knot offers interactive mathematics puzzles and educational material.
About Cut The Knot
Cut The Knot (Interactive Mathematics Miscellany and Puzzles) is a website of interactive mathematics puzzles, games, articles and reference material. Its homepage describes it as an encyclopedic collection for all grades. Topics include arithmetic, algebra, geometry, probability, trigonometry, logic, calculus, fractals, combinatorial games, visual illusions and fallacies, with a glossary and index.
The site was started in 1996 by Alexander Bogomolny, whose last update was on July 6, 2018. After his death in July 2018, his family and friends asked the Wolfram Foundation to maintain and update the site, and the homepage says more details would follow. A separate commemorative book of probability riddles, published on November 17, 2020 in collaboration with STEM Academic Press and Wolfram Media, is sold on Amazon, with proceeds going to Alexander's family.
Key features
- Arithmetic games, word problems and online practice exercises
- Logic puzzles including Venn diagrams and Lewis Carroll's logic game
- Interactive fractal pages covering the Mandelbrot set and Julia sets
- Collection of visual illusions such as the Müller-Lyer and Necker cube
- Combinatorial games such as Nim, Kayles and Wythoff's Nim
- Calculus topics including Riemann sums and Taylor series for cosine
Best for: Students at a range of grade levels and teachers looking for interactive mathematics puzzles and explanatory articles.
Good for
- Covers many topics, from arithmetic and algebra to calculus and fractals.
- Organized into subject sections, with an index and glossary.
- The homepage describes the material as suitable for all grades.
Watch out for
- The homepage says details of the maintenance arrangement after Alexander Bogomolny's death were still to come, so future updates are not specified.
Cut The Knot at a glance
- Website
- cut-the-knot.org
- Category
- Education & Learning › Mathematics Learning
- Type
- Website
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
Cut The Knot alternatives
Tools and sites you could use instead, ranked by how closely they match.
Mathigon offers interactive mathematics learning resources through its online mathematical playground.
LibreTexts Mathematics provides curated textbook materials that readers can use directly or adapt into customized remixes.
MadAsMaths maintains a mathematics resource archive for learners and teachers looking for study material.
SchoolYourself offers interactive online math videos, lessons, and tutoring, with blog and account links.
Free
24 alternativesStitz-Zeager provides free, open precalculus materials covering college algebra, trigonometry, and precalculus.
Popular in Mathematics Learning
Well-known listings from the same topic.
CoolMathcoolmath.comProject Eulerprojecteuler.netMath Planetmathplanet.comAlgebra Rulesalgebrarules.comWolfram|Alphawolframalpha.comSmartschooljoinsmartschool.com
Cut The Knot FAQ
Who created the website?
Alexander Bogomolny started the site in 1996. After his death in July 2018, his family and friends asked the Wolfram Foundation to serve as steward for maintenance and updates.
Is there a related book?
Yes. A commemorative book of probability riddles was published on November 17, 2020, in collaboration with STEM Academic Press and Wolfram Media. It is sold on Amazon, and all proceeds go to Alexander's family.
What grade levels does the site cover?
The homepage describes it as a collection of math resources for all grades.
Is something wrong or out of date?
Tell us and an editor will check it.
Own this website?
Claim this listing
Claim the listing and suggest updates yourself. An editor checks every claim first.