Some say that numbers aren't as important as actual functions, but we say they are! :-) For anyone who has wondered why 13 is unlucky, why you can't eat pi, or why 1 is the multiplicative identity, this is the category you've been searching for since grade school. Whatever intellectual curiosity has been nagging at you since you first wrote the number 5, you will be likely to find an answer to your question here. And if not, submit your own! Also: Definitions of important constants, formulas to compute them and formulas that use them.
Please just submit links that contain information about numbers, e.g. about pi, e, fibonacci numbers, mathematical constants, phi - The Golden Ratio, and others.
There are two common uses of Zero: One use is as a empty place indicator in our place-value number system. Hence in a number like 2106 the zero is used so that the positions of the 2 and 1 are correct. Clearly 216 means something quite different. The second use of zero is as a number itself in the form we use it as 0. There are also different aspects of zero within these two uses, namely the concept, the notation, and the name.

This category is concerned with the second use, the number zero itself. It lists sites that discuss the history, use and specialities of the number zero.

Additionally such topics as "division by zero" are listed.
Please just submit sites discussing the number zero in this category. For other special numbers, please use either one of the other subcategories or the main category for specific numbers.


e = 2.71828182 It has been called the logarithmic constant, Napier's number, Euler's constant, and the natural logarithmic base. The constant plays a key role in descriptions of phenomena such as radioactive decay and population growth and, in the financial world, and in calculations of compound interest.
Fibonacci numbers, named after Italian mathematician Leonardo Fibonacci, are the numbers in the Fibonacci sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, . . . , each of which, after the second is the sum of the two previous ones.
Used in many context, infinity can have many meanings. The sequence of natural numbers, 1, 2, 3, ..., is said to be infinite. In geometry, the number of points on a line is said to be infinite. Time is often assumed to be infinite, in the sense that it had no beginning, or will have no end, or both. Space is often assumed to be infinite in extent. Infinity is not bound by the basic rules and axioms of math and can destroy logic in arithmetic.
Integers are positive and negative whole numbers, such as 1, 2, 3. Numbers that are most common and used everyday, but here are some distinctive facts about these numbers not everyone knows.
Please submit sites containing distinctive fact or unique properties about integers.


Phi is the Greek letter representing the golden ratio, also called the golden mean or the golden proportion. Break a line segment into two such that the ratio of the whole to the longest segment is the same as the ratio of the two segments, that ratio is the golden ratio. Phi = 1.618034...


Pi = 3.1415926535... An irrational number, a never ending yet never repeating decimal, Pi has been calculated and explored throughout history from the ancient times to the present.
Please submit sites solely dedicated to the number Pi.