rule of three

  1. the method of finding the fourth term in a proportion when three terms are given.

Origin of rule of three

First recorded in 1585–95

Words Nearby rule of three Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use rule of three in a sentence

British Dictionary definitions for rule of three

rule of three

  1. a mathematical rule asserting that the value of one unknown quantity in a proportion is found by multiplying the denominator of each ratio by the numerator of the other

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