Los 10 principales competidores de mathforum.org

mathworld.wolfram.com

A connected graph G is distance-regular if for any vertices x and y of G and any integers i,j=0, 1, ...d (where d is the graph diameter), the number of vertices at distance i from x and distance j from y depends only on i, j, and the graph distance between x and y, independently of the choice of x and y. In particular, a distance-regular graph is a graph for which there exist integers b_i,c_i,i=0,...,d such that for any two vertices x,y in G and distance i=d(x,y), there are exactly c_i...

math.com

free math lessons and math homework help from basic math to algebra, geometry and beyond. students, teachers, parents, and everyone can find solutions to their math problems instantly.

cut-the-knot.org

an encyclopedic collection of math resources for all grades. arithmetic games, problems, puzzles, and articles

whyslopes.com

This site www.whyslopes.com, authored by Alan Selby at www.whyslopes.com, offers online books,an plug and play content management system for home and math-science websites, an alternative mathematics & logic skill development steps and for instruction or self-instruction, an alternative mathematics & logic skill development program. Its small steps aim to ease and avoid common fears and difficulties by filling gaps in skill and concept development and by providing more gradual paths and so avoid paths of steepest ascent where in the past steps have been too large or in retrospect, missing. The site content managementis employed to present site material, site display options and site navigation systems. In it mathematical expressions are presented using a local or online version of mathjax.

sosmath.com

see relevant content for mathclinic.com

purplemath.com

Purplemath (PM) kinda happened by accident. Read here about PM's author, Elizabeth Stapel, and about Purplemath, including the origin of its name.

coolmath.com

cool math has free online cool math lessons, cool math games and fun math activities. really clear math lessons (pre-algebra, algebra, precalculus), cool math games, online graphing calculators, geometry art, fractals, polyhedra, parents and teachers areas too.