perfect number

noun

Mathematics.

a positive number that is equal to the sum of all positive integers that are submultiples of it, as 6, which is equal to the sum of 1, 2, and 3.

perfect number

noun

an integer, such as 28, that is equal to the sum of all its possible factors, excluding itself

perfect number

A positive integer that equals the sum of all of its divisors other than itself. An example is 28, whose divisors (not counting itself) are 1, 2, 4, 7, and 14, which added together give 28.

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Word History and Origins

Origin of perfect number¹

Middle English word dating back to 1350–1400

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Example Sentences

Examples have not been reviewed.

Soil experts differ on the perfect number between acidity and alkalinity, but the sweet spot is generally believed to be between 6.5 and 7.2, Wallace said, and some scientists believe plants in SoCal can tolerate alkalinity as high as 7.9.

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“There is no perfect number to send, no perfect geography to send it out to,” Galperin said.

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"Without the scientific study, it can’t be said what will be the perfect number for Mount Everest," he said.

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Still, Pi is not a perfect number.

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“It’s one of those days, every shot you hit just has a perfect number,” An said.

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perfectly perfecto

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