# How do you tell if a two's complement number is negative?

**number**is commonly referred to as the sign-magnitude notation and

**if**the sign bit is “0”, the

**number**is positive.

**If**the sign bit is “1”, then the

**number is negative**.

Furthermore, is the two's complement of a number always a negative number?

**Negative** integers are stored as the **two's complement** of their absolute value, i.e. of the corresponding positive integer. The **two's complement** of a positive **number** is, when using this notation, a **negative number**.

**Two's complement**is a mathematical operation on binary

**numbers**, and is an example of a radix

**complement**. It is used in computing as a method of signed

**number**representation. The

**two's complement**of an N-bit

**number**is defined as its

**complement**with respect to

**2**

^{N}.

Similarly, you may ask, how are negative numbers represented in binary?

**Negative Numbers** The simplest is to simply use the leftmost digit of the number as a special value to **represent** the sign of the number: 0 = positive, 1 = **negative**. For example, a value of positive 12 (decimal) would be written as 01100 in **binary**, but **negative** 12 (decimal) would be written as 11100.

If the **number** is **negative** then it is represented using **1's complement**. First represent the **number** with positive sign and then take **1's complement** of that **number**. (ii) Take **1's complement** of 0 0101 and that is **1** 1010.

**One's Complement**.

Binary number | 1's complement |
---|---|

111 | 000 |