 On both apparent and absolute magnitude scales , the smaller the magnitude number , the brighter the star ; the larger the magnitude number , the <unk> the star . The brightest stars , on either scale , have negative magnitude numbers . The variation in brightness ( <unk> ) between two stars is calculated by <unk> the magnitude number of the brighter star ( mb ) from the magnitude number of the <unk> star ( <unk> ) , then using the difference as an exponent for the base number 2 @.@ 512 ; that is to say : 
