rule of three

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noun Mathematics.

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

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Origin of rule of three

First recorded in 1585–95

Words nearby rule of three

rule of eleven, rule of engagement, rule of law, rule of outlet, rule of the road, rule of three, rule of thumb, rule out, ruler, rulership, Rules

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

How to use rule of three in a sentence

Obviously, the first obligation of all liberal democratic governments is to enforce the rule of law.
Ayaan Hirsi Ali: Our Duty Is to Keep Charlie Hebdo Alive|Ayaan Hirsi Ali|January 8, 2015|DAILY BEAST
Their three-day scientific outing was paid for by Epstein and was big success.
Sleazy Billionaire’s Double Life Featured Beach Parties With Stephen Hawking|M.L. Nestel|January 8, 2015|DAILY BEAST
Three on-the-record stories from a family: a mother and her daughters who came from Phoenix.
I Tried to Warn You About Sleazy Billionaire Jeffrey Epstein in 2003|Vicky Ward|January 7, 2015|DAILY BEAST
One of the other cops fired three times and those who were still able to give chase did.
Shot Down During the NYPD Slowdown|Michael Daly|January 7, 2015|DAILY BEAST

So I was looking back at the years, and that really popped out at me, those three years.
Patton Oswalt on Fighting Conservatives With Satire|William O’Connor|January 6, 2015|DAILY BEAST
It is thinner than that of chronic bronchitis, and upon standing separates into three layers of pus, mucus, and frothy serum.
A Manual of Clinical Diagnosis|James Campbell Todd
I waited three months more, in great impatience, then sent him back to the same post, to see if there might be a reply.
The Boarded-Up House|Augusta Huiell Seaman
There are three things a wise man will not trust: the wind, the sunshine of an April day, and woman's plighted faith.
Pearls of Thought|Maturin M. Ballou
In cross-section the burrows varied from round (three inches in diameter) to oval (three inches high and four inches wide).
Summer Birds From the Yucatan Peninsula|Erwin E. Klaas
It separates into three layers upon standing—a brown deposit, a clear fluid, and a frothy layer.
A Manual of Clinical Diagnosis|James Campbell Todd

British Dictionary definitions for rule of three

rule of three

noun

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

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012