# Constants > 128-bit complex number mathematical constants
## Usage ```javascript var constants = require( '@stdlib/constants/complex128' ); ``` #### constants 128-bit complex number mathematical constants ```javascript var c = constants; // returns {...} ```
- [`NUM_BYTES`][@stdlib/constants/complex128/num-bytes]: size (in bytes) of a 128-bit complex number.
## Examples ```javascript var objectKeys = require( '@stdlib/utils/keys' ); var constants = require( '@stdlib/constants/complex128' ); console.log( objectKeys( constants ) ); ```