If you’re fond of both language and math, you surely already know that in the phrase “5 minus 3” the number 5 is the minuend and the number 3 is the subtrahend. Since that’s not news, it’s a good thing that 5 less 3 is not really the subject of this bit of trivia. No, the real subject is this: when you have a phrase like 5 take away 3, how come there are so many different ways to express it? “Less,” “minus,, “take away,” and probably a couple of others too.
“Minus” is a pretty specific and technical term, and as such is less (interesting than “less.” “Take away” simply describes the operation. The most interesting term here is probably “less”.
The word less goes back to Old English, and although its had several meanings over the centuries since, its original meaning was (as nearly as anyone can be sure) the same as “fewer.” The oldest citation identified so far comes from a translation into Old English of De Consolatione Philosophiae by Boethius:
“Swa mid læs worda swa mid ma, swæðer we hit gereccan magon” (“So we may prove it with less words as with more, whichever of the two”).
The oldest use of “less” specifically meaning “minus” is from this, which is from sometime around 1160:
“He rixode twa læs .xxx. geara” (“He ruled for 30 years less two”).
That particular quotation is also interesting in that “two” is spelled out (twa) but 30 is expressed in numerals (xxx) — which is a pattern you still see today. Except not usually in Roman Numerals.
Now once you take away 3 from 5, what you have left is less, right? Or is it fewer? In general, “less” is more likely to refer to amount, while “fewer” is less likely to mean amount and more likely to have to do with a smaller number — that is, an enumerated quantity. Just like less, fewer (well, actually its root word “few”) goes back to Old English. “Few” is used in Beowulf, which dates from around the 700s. If you’ve read The Name of the Rose you may recall a reference or two made to the Venerable Bede. He was a real person, and left some writings around the 900s in which he used the word “few.” The word “fewer” — which technically is the comparative form of “few” — apparently took a while longer to arrive; the first citation we have is from 1340.
Nowadays it’s not unusual to find someone’s grammatical nose has been put out of joint by finding a case where “less” is used for quantity instead of “fewer.” This is a pretty recent phenomenon. “Less” and “fewer” were used pretty much interchangeably for about a thousand years before the idea arose that you ought to use one for amount and the other for quantity. In fact, the idea appears to have been promoted by just one person: a grammarian named Robert Baker. In 1770 he wrote that “…’fewer’ would be “not only more elegant … but more strictly proper’ than ‘less’ in a phrase like “no less than a hundred.”
The rule has been further refined since Baker’s day. A grammatical stickler nowadays would point out that whether you should use “less than a hundred” or “fewer than a hundred” depends entirely on what the hundred is referring to. And here it gets extremely nitpicky: if you really care about this distinction, you’d use “less” when your “hundred” refers to something that exists as inherently discrete items, and “fewer” when your “hundred” is a measurement of something that exists as one aggregate amount. Gallons of maple syrup, for example, versus pancakes. When you have a hundred gallons of syrup, you basically have a big tank of syrup and the hundred refers to an amount. But in the case of pancakes, you have a hundred separate things, and that’s a quantity.
Grammarian nitpicking aside, if you look at actual usage, the situation seems to be reverting to the traditional pre-1770 understanding — fewer and less are used relatively interchangeably and understood to mean the same thing. After all, if you count the weight of history, the words have been considered different far less — that is, for fewer centuries — than they’ve been the same. You know this because 2017 take away 1770 is much smaller than 1770 minus 800. Wait… “smaller”?!?