The Abacus
The Art of Calculating with Beads. Very detailed Java demonstrations
of addition and subtraction.
The Chinese Abacus Clear, detailed explanations and diagrams. (Better than the next link)
The Chinese Abacus Another abacus; explanations a bit abstract; includes a Java simulation of an abacus and demonstrations of addition, subtraction, multiplication, and division.
Chinese Abacus Explanations very hard to follow.
My Geometry Teacher Tools for solving Analytic Geometry exercises.
Distrance from a point to a line
Review of Analytic Geometry Check also the homepage, Stewart Calculus for excellent Calculus resources for all of his books.
Continuity and Infinitesimals Stanford Encyclopedia of Philosophy. See also: Constructive Mathematics, and Intuitionist Logic.
Introduction to Real Analysis By William E. Trench. Free PDF copy of the book published by Prentice Hall, 2002 ISBN: 0130457868.
MathCS - Analysis Resources related to Analysis, suitable for self-study or to accompany a course in calculus, introductory real analysis, or introductory complex analysis. Includes Interactive Real Analysis, an online, interactive textbook for Real Analysis or Advanced Calculus, and Interactive Complex Analysis, an online, interactive textbook for Complex Analysis.
Mathematical Analysis I by by Elias Zakon, ISBN 1-931705-02-X, published by The Trillia Group, 2004. Currrent version, released March 10, 2009, can be downloaded free for self-study.
Nonstandard Analysis and the Hyperreals by Jordi Gutierrez Hermoso. A gentle introduction.
Steven Strogantz, New York Times
Mathematical articles for the general reader; a new article every Sunday. Links to previous articles in the series.
Complex Numbers and Trigonometry By Abraham P. Hillman, Gerald L. Alexanderson, and Mervin E. Newton. This text has been placed on the web as a public service by the Department of Mathematics and Computer Science of Thiel College. It presents an innovative introduction to trigonometry through the use of complex numbers.
Discrete Mathematics Applets Etc. Susanna S. Epp, DePaul University
Cardinal Numbers Nancy McGough
Constructive Mathematics Douglas Bridges, Stanford Encyclopedia of Philosophy
Foundations of Mathematics An online resource center about the foundations of mathematics. Intended to be a textbook and a comprehensive reference, but advanced research topics are not included. The author has attempted to select high-quality material on the web. See also The Beauty of Math in Alexander Sakharov's website.
Infinite Ink - Mathematics Infinite Ink's primary mathematical interest is foundations of mathematics, including standard and non-standard logics, set theories, and other mathematical frameworks.
Clay Mathematics Institute Dedicated to increasing and disseminating mathematical knowledge.
MAA Online The Mathematical Association of America
Interactive Real Analysis Online, interactive textbook for Real Analysis or Advanced Calculus in one real variable. It deals with sets, sequences, series, continuity, differentiability, integrability (Riemann and Lebesgue), topology, and more.
ClassicalRealAnalysis.com This web site contains current information on the two real analysis textbooks, Elementary Real Analysis and Real Analysis by Andrew M. Bruckner, Judith B. Bruckner and Brian S. Thomson. PDF copies of the second edition can be downloaded.
The Axion of Choice
The Continuum Hypothesis Nancy McGough
A Crash Course in the Mathematics of Infinite Sets Peter Suber, Earlham College
Set Theory
Thomas Jech, Stanford Encyclopedia of Philososphy. Look also under set theory in
the table of contents, and at the excellent links a search for "set theory" generates.
Set Theory and the Construction of Numbers Presents the Zermelo-Frankel axioms for set theory and develops a model for the axioms. The concept of number is a consequence of this model.
Zermelo-Fraenkel Set Theory with Choice (FZC) axioms Metamath
Zorn's Lemma and Some Applications Keith Conrad, University of Connecticut.
Trigonometry - A Review The Undergraduate Computational Engineering and Sciences (UCES) Project, Krell Institute.
Trigonometry TheMathPage
Algebraic Topology Allen Hatcher, Cornell University. A version of the book printed by Cambridge University Press in 2002 is available for download. So are chapters of Topology of Numbers, as they become available.