# 1

== 1 ==

**1** (one, also called **unit**) is a number and a numeral. It represents a single entity and is the first positive integer. In the decimal system, it is the first digit and the basis of counting.

## Mathematics[edit | edit source]

In mathematics, 1 is the multiplicative identity. This means that any number multiplied by 1 remains unchanged. For example, \( a \times 1 = a \) for any number \( a \). It is also the first natural number and the first odd number.

### Properties[edit | edit source]

- 1 is the only number for which the reciprocal is equal to itself.
- 1 is the only positive integer that is neither prime nor composite.
- In exponentiation, any number raised to the power of 1 is the number itself, i.e., \( a^1 = a \).

## Science[edit | edit source]

In science, 1 is often used as a unit of measurement. For example, 1 meter is the base unit of length in the International System of Units (SI).

## Computing[edit | edit source]

In computing, 1 is used in binary code as one of the two binary digits, 0 and 1, which are the foundation of all modern computer systems.

## Philosophy and Religion[edit | edit source]

In many philosophical and religious contexts, 1 is often associated with unity and the concept of a single, all-encompassing entity. For example, in monotheism, 1 represents the belief in a single deity.

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Contributors: Prab R. Tumpati, MD