# A to Z of Excel Functions: The DEC2BIN Function

11 June 2018

This function converts a decimal number (base 10) to binary (base two).

The **DEC2BIN **function employs the following syntax to operate:

**DEC2BIN(number, [places])**

The **DEC2BIN** function has the following arguments:

**number:**this is required and represents the decimal integer you wish to convert. If**number**is negative, valid place values are ignored and**DEC2BIN**returns a 10-character (10-bit) binary number in which the most significant bit is the sign bit. The remaining 9 bits are magnitude bits. Negative numbers are represented using two's-complement notation**places:**this argument is optional. This is the number of characters to use. If**places**is omitted,**DEC2BIN**uses the minimum number of characters necessary. The argument**places**is useful for padding the return value with leading 0s (zeros).

**Two's complement** is a mathematical operation on binary numbers, as well as a binary signed number representation based on this operation. The two's complement of an **N**-bit number is defined as the complement with respect to 2** ^{N}**; in other words, it is the result of subtracting the number from 2

**. This is also equivalent to taking the ones' complement and then adding one, since the sum of a number and its ones' complement is all 1 bits. The two's complement of a number behaves like the negative of the original number in most arithmetic, and positive and negative numbers can coexist in a natural way.**

^{N}It should be further noted that:

- if
**number**< -512 or if**number**> 511,**DEC2BIN**returns the*#NUM!*error value - if
**number**is nonnumeric,**DEC2BIN**returns the*#VALUE!*error value - if
**DEC2BIN**requires more than**places**characters, it returns the*#NUM!*error value - if
**places**is not an integer, it is truncated - if
**places**is non-numeric,**DEC2BIN**returns the*#VALUE!*error value - if
**places**is zero or negative,**DEC2BIN**returns the*#NUM!*error value.

Please see my example below:

*We’ll continue our A to Z of Excel Functions soon. Keep checking back – there’s a new blog post every business day.*

*A full page of the function articles can be found here. *