zero in on

: the arithmetical symbol 0 or 0̸ denoting the absence of all magnitude or quantity

: additive identity

: a value of an independent variable that makes a function equal to zero

: of, relating to, or being a zero

: having no magnitude or quantity : not any

: having no phonetic manifestation

: to determine or adjust the zero of

: to concentrate firepower on the exact range of

: to bring to bear on the exact range of a target