## 09 October 2007

### Math notation

I'm not accustomed to thinking of mathematical notation as having a history. After all, the equals sign, "=," just is what it is. When did I first encounter that sign? First grade? I can't remember, and this "time out of mind" quality is what protects it from historical inquiry.

But of course such notation does have a history. The number zero has a history that supports a legion of scholars, as does the history of pi. How we write a number is connected with the way we think about numbers, so that writing "0" is something very different from writing "zero."

Still, let's not drift away into number theory. Let's stick with a sample of what one might call "pure notation," the equal sign. This = was invented in 1557 by Robert Recorde, of Wales, in what was actually the first book on algebra printed in the British isles.

Here's the URL for an image of the page in which the equal sign first appears.

http://members.aol.com/jeff94100/witte.jpg

You'll notice if you go to that page that Mr. Recorde used two rather longish parallel lines.

The old-fashioned fonts can make comprehension difficult. So I'll reproduce the final paragraph for you, just before his list of seven equations.

"Howbeit, for each alteration of equations, I will propound a few examples, because the extraction of their roots, may the more aptly be wrought. And to avoid the tedious repetition of these words, 'is equal to,' I will set as I do often in working, a pair of parallels, or remote lines of one length, thus: ===========, because no two things can be more equal. And now mark these numbers."

We should all have as solid a claim to immortality as Mr. Recorde and his scheme for the avoidance of tedious repetition.

But of course such notation does have a history. The number zero has a history that supports a legion of scholars, as does the history of pi. How we write a number is connected with the way we think about numbers, so that writing "0" is something very different from writing "zero."

Still, let's not drift away into number theory. Let's stick with a sample of what one might call "pure notation," the equal sign. This = was invented in 1557 by Robert Recorde, of Wales, in what was actually the first book on algebra printed in the British isles.

Here's the URL for an image of the page in which the equal sign first appears.

http://members.aol.com/jeff94100/witte.jpg

You'll notice if you go to that page that Mr. Recorde used two rather longish parallel lines.

The old-fashioned fonts can make comprehension difficult. So I'll reproduce the final paragraph for you, just before his list of seven equations.

"Howbeit, for each alteration of equations, I will propound a few examples, because the extraction of their roots, may the more aptly be wrought. And to avoid the tedious repetition of these words, 'is equal to,' I will set as I do often in working, a pair of parallels, or remote lines of one length, thus: ===========, because no two things can be more equal. And now mark these numbers."

We should all have as solid a claim to immortality as Mr. Recorde and his scheme for the avoidance of tedious repetition.

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