Of or pertaining to currency, especially to coins. / Of or pertaining to numismatics.

A phone number as a mnemonic whose letters translate into numbers.

plural of 800 number

(idiomatic) to do something exactly, precisely, or in a formulaic way.

(mathematics) A mathematician who specializes in number theory

plural of number theorist

(US) A pencil which produces a specific shade of dark gray. One can usually identify a number 2 pencil by looking for the number "2" conspicuously emblazoned on the pencil. Often required for test-taking and the completion of official forms.

plural of cardinal number

A performance rating of diesel fuel corresponding to the percentage of cetane in a mixture with isocetane (or, formerly, methylnaphthalene) that would have the same performance.

plural of 900 number