National Council of Teachers of Mathematics
The Math Forum: Beat the Calculator!
Find more than 500 "mental calculation tricks" that will help you square numbers, add, multiply divide, subtract, and find percentages. A great resource for advance math students, gifted children, and teachers wanting to find ideas for...
Other
Problems in the Points Contest of Ko Mal
Learn about the annual KoMal competition in mathematics, physics, and information technology, and challenge your ability to solve problems involving advanced algebra, logic, and other related topics through the tests provided at this site.
Braingle
Braingle: Probability Brain Teasers
Check out the variety of probability brain teasers at this site, which you can sort by popularity and difficulty.
Braingle
Braingle: Math Brain Teasers
Check out the variety of math brain teasers at this site, which you can sort by popularity and difficulty.