1,000,000,000 (one billion, short scale; one thousand million or milliard, long scale) is the natural number following 999,999,999 and preceding 1,000,000,001.
In scientific notation, it is written as 109.
A billion traditionally equated to one million, million, (1,000,000,000,000) though the short scale (American English) billion of merely one thousand million (1,000,000,000) has been adopted in finance and increasingly in other fields. The unambiguous term thousand million has the same meaning in both scales.
In South Asian English, it is known as 100 crore or 1 arab.
The term milliard can also be used to refer to 1,000,000,000; this name very often appears in other languages.
This terminology is rarely used in English outside of British English. The SI prefix giga indicates 1,000,000,000 times the base unit.
See Orders of magnitude (numbers) for larger numbers; and long and short scales.
The facts below give a sense of how large 1,000,000,000 (109) is in the context of time according to current scientific evidence:
A number is a mathematical object used to count and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers.
Mathematical operations are certain procedures that take one or more numbers as input and produce a number as output. Unary operations take a single input number and produce a single output number. For example, the successor operation adds one to an integer, thus the successor of 4 is 5. Binary operations take two input numbers and produce a single output number. Examples of binary operations include addition, subtraction, multiplication, division, and exponentiation. The study of numerical operations is called arithmetic.
A notational symbol that represents a number is called a numeral. In addition to their use in counting and measuring, numerals are often used for labels (telephone numbers), for ordering (serial numbers), and for codes (e.g., ISBNs).