rule of three

American  

noun

Mathematics.

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

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rule of three British  

noun

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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Etymology

Origin of rule of three

First recorded in 1585–95

Example Sentences

See Examples For:

rule of three

And there are exceptions to this rule of three okazu, one soup, one grain and pickles: All-in-one dishes, such as noodle soups and grain bowls.

From Washington Post ● Dec. 30, 2021

By the rule of three, however, that means it's likely to be offered one more time.

From Salon ● Apr. 10, 2019

The rule of three as the most stable structure can be subverted to afford you double the scapegoats.

From Slate ● Apr. 2, 2019

As Ramakrishnan says: “The rule of three is inappropriate today.”

From The Guardian ● Sep. 30, 2018

He is at liberty to deny and ridi- cule the rule of three, conic sections, and even the multiplication table.

From The Works of Robert G. Ingersoll, Vol. 5 (of 12) Dresden Edition?Discussions by Ingersoll, Robert Green