Mathematicians know best

Far be it for me to be against the pedantic. All hail the pedants; force the illiterati to feel foolish for their errors.

Or, as is more often the case, allow the illiterati to mock the pedantic for being anal and subsequently increase hatred on both sides of the grammar divide.

However much I agree with the pedant army, there is one commonly quoted error that irks me.

The pedants state that the use of "less than" is frequently incorrect and should be "fewer than". The usual example is at a fast checkout queue which has signage indicating "20 items or less", causing the hackles to rise in those who argue the following:

Less is used for a non-discrete quantity, for example: less milk. You can reduce the amount of milk by any amount, a drop, a cup, a drizzle, however much you like. If talking about a discrete quantity, such as bottles of milk, which can only be reduced in whole numbers, you should say "fewer than 7 bottles".

And so the mathematical part of my brain comes into action.
I instinctively want to correct that 7 to x, because in that sentence any number at all could fit. 7 is a number plucked from nowhere and which doesn't really belong there.

And so the sentence would read "fewer than x bottles of milk". Better, they say.

Except "fewer than" is not a mathematical term. In mathematics, you would write it as "less than x bottles of milk", because "less than" IS a mathematical term. Of course in maths, you would have discarded most of the words and would simply be dealing with < x, but that is another matter.

In the supermarket queue scenario, the number of items must be less than or equal to 20. Or to be more concise: 20 or less.
A correct mathematical term, and therefore appropriate to me.