In my prime

The previous article was the 181st in this series, and you’ll forgive the eternal math teacher for saying that that post certainly makes me feel like I’m in my prime—not only because 181 is a lot of articles for a little over half a year, but also because 181 is what mathematicians call a número primo/prime number. The primes are one of three categories into which the positive whole numbers are divided. Most common are the composites, each member of which can be represented by a rectangular array of dots with the same number of dots in each row. For example, we can represent the composite number 12 as three rows of four dots each:

•    •    •    •
•    •    •    •
•    •    •    •

In contrast, a prime number cannot be represented as a rectangular array. We may try with the prime number 7, for example, but we have one dot too few to fill up a second row

•    •    •    •
•    •    •

or we have a surplus dot that spills over into a third row

•    •    •
•    •    •

The only possible arrangement for 7 is

•    •    •    •    •    •    •

In other words, all the dots end up in the first—and only—row. That’s one way of explaining why such numbers are called prime, from the Latin word for ‘first,’ primus (which we discussed in the recent entry for primavera). Historically, the ancient Greeks had the notion that the primes are first in importance, the fundamental type of whole number; the composites are secondary because they can always be expressed as products of primes (which amounts to saying that we can make rectangular arrays of dots to represent them).

Ironically, as fortunate readers may remember having been taught during their years en la primaria/in primary school, the Greeks placed the very first positive whole number, 1, which was of prime importance to them, in a category of its own. The ancients accorded the number 1 that distinction for being the first [positive whole] number, the generator of all others.

All of this tempts me to proclaim the primacía/primacy of mathematics over everything else, but I would never do such a thing in a column about etymology, where words are our prime consideration.

© 2011 Steven Schwartzman

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2 Comments (+add yours?)

  1. Don Levesque
    Mar 28, 2011 @ 19:22:14

    Bien dicho/well said!

    Reply

  2. wordconnections
    Mar 28, 2011 @ 19:33:13

    ¡Gracias/Thanks! I was really primed for this post.

    Reply

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If you encounter an unfamiliar technical term in any of these postings, check the Glossary in the bar across the top of the page.
©2011–2016 Steven Schwartzman
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