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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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

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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
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