# Binary

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**Binary** is a way to show whole numbers using only 1 and 0. Computers work in binary.

## [edit] Number System

Binary numbers can be changed to decimal (base 10, the kind most people use) in a simple way. The value of the bit (binary 1 or 0) on the right side of the number is 1. Every other bit has a value two times the value of the bit to its right. Add the values of every bit that is a 1 together to get the decimal number.

For example, the binary number **101** is **5** in decimal. The bit on the right is 1 and has a value of 1. The middle bit has a value of 2 (1 times 2), but it is a 0, so it is not added. The bit on the left is 1 and has a value of 4 (2 times 2). The bits that are 1's have values of 1 and 4. 1 + 4 = **5**.

## [edit] Computers

All computers use binary at the lowest level. Most computer storage, like compact discs and DVDs, use binary to represent large files.

With computers, 8 binary bits together is called a *byte*. The size of files is commonly measured in *kilobytes* or *megabytes*. A kilobyte is 1,024 bytes. A megabyte is 1,024 kilobytes, or 1,048,576 bytes. While *kilo* commonly means 1,000, it is different here because 1,024 is an exponent of 2.