by the numbers

• by-the-numbers (as adjective)

The origin of this phrase goes back to the American Revolutionary War where a book containing numbered positions for rifle and bayonet practice was used to train soldiers. In the book, each diagram was numbered.

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by the numbers

1. (idiomatic) exactly, precisely, or in a formulaic way.

   Synonyms: by the book, by numbers

• paint-by-numbers