Minggu, 06 November 2011

Classification of numbers ( dicopy dari Wikipedia, the free encyclopedia )

Different types of numbers are used in many cases. Numbers can be classified into sets, called number systems. (For different methods of expressing numbers with symbols, such as the Roman numerals, see numeral systems.)

Number systems
 \mathbb{N} Natural 0, 1, 2, 3, 4, ... or 1, 2, 3, 4, ...
 \mathbb{Z} Integers ..., −5, −4, −3, −2, −1, 0, 1, 2, 3, 4, 5, ...
- Positive integers 1, 2, 3, 4, 5, ...
 \mathbb{Q} Rational ab where a and b are integers and b is not zero
 \mathbb{R} Real The limit of a convergent sequence of rational numbers
 \mathbb{C} Complex a + bi where a and b are real numbers and i is the square root of −1

[edit] Natural numbers

The most familiar numbers are the natural numbers or counting numbers: one, two, three, and so on