About Number 9. Nine is the smallest odd composite number and the minimum composite odd number that is no Fermat pseudoprime. It is the smallest natural number n, for each non-negative integer can be represented as a sum of at most n positive cubes (see Waring's problem), and the smallest positive integer n for which n squares in pairs of different positive edge length exist, the can be put together to form a rectangle. Number Nine is the number which (other than 0) as a single digit checksum generally occurs (in decimal number system) after multiplication by an arbitrary integer always even, and the number which is added to any other (except 0 and -9), as a single digit checksum the same result as the starting number itself - ie it behaves quasi-neutral.
About Number 0. The number zero is the number of elements in an empty collection of objects, mathematically speaking, the cardinality of the empty set. Zero in mathematics by depending on the context variously defined objects, but often can be identified with each other, that is considered to be the same object, which combines several properties compatible with each other. As cardinal numbers (number of elements in a set) are identified with special ordinals, and the zero is just the smallest cardinal number is zero - elected as the first ordinal - in contrast to common parlance. As finite cardinal and ordinal it is depending on the definition often counted among the natural numbers. The zero is the identity element for addition in many bodies, such as the rational numbers, real numbers and complex numbers, and a common name for a neutral element in many algebraic structures, even if other elements are not identified with common numbers. Zero is the only real number that is neither positive nor negative.
What Is An Odd Number?
An odd number is an integer which is not a multiple of two. If it is divided by two the result is a fraction. One is the first odd positive number. The next four bigger odd numbers are three, five, seven, and nine. An integer that is not an odd number is an even number.
An even number is defined as a whole number that is a multiple of two. If an even number is divided by two, the result is another whole number. On the other hand, an odd number, when divided by two, will result in a fraction. Since odd and even numbers are defined only in reference to the set of integers (..., -3, -2, -1, 0, 1, 2, 3, ...), all negative numbers can also be either odd or even.