Exactly as the rules, directions, or plans dictate. Primarily heard in UK. If we all focus and do this by numbers, then we should have no trouble getting it finished. The military strike was executed perfectly and by numbers.
by numbersfollowing simple instructions identified by numbers; mechanically.
This phrase alludes to painting by numbers , a painting kit with a canvas on which numbers have been marked to indicate which colour of paint should be applied at which place. US English uses the variant by the numbers .
1992 Canadian Yachting We discovered navigation by numbers as our beamy flotilla floated from buoy to buoy reading off the charts like a road map.