- from Numberphile
Two nations divided by a common language
And about two hundred years of new songs and dancing
But the difference is language and just the bits you got wrong
'Cause we were the ones who invented the language
- Two Nations, The Streets.
English is a vulture of a language, the bastard child of the Angles' own native language and the waves of invaders' languages such as the Saxons, the Vikings, the Normans and anything else it could be bothered to steal from. Like a vulture, it also steals without remorse and mangles words from different sources.
I'm sure that pure classicists would cry foul at a word like "television" which jams together both Greek and Latin words, into an hideous, twisted, ugly monster.
So then, why should there be squabbles about which word is right, "math" or "maths"? English is already perfectly capable of twisting words to its own ends and surely English is flexible enough to accommodate both? Obviously it does this by virtue of the fact that both variants exist quite happily and question of why this debate even exists is mainly due either the question of whether dictionaries and standards should be prescriptive or descriptive, but that question is for another discussion.
To the matter at hand. In English, the vast majority of plurals end with an "s" as in "plants and birds and rocks and things" and "es" as in "foxes, boxes, hatches and watches". "Maths" it would seem is an ordinary plural, except that there is no singular "Math"; not even in American English.
The word "mathematics" in English derives from the Greek word "mathematica" which itself is plural, and in the Greek sense it was, being used to describe the plural of arithmetic, geometry and algebra etc. More recently it has grown to include calculus, complex and imaginary mathematics etc. There is a case to be made for "mathematics" to be plural but you do not count "nine maths" like you would "five cats" of "one hundred sheep"
On the face of it, Mathematics is then either a collective noun or a mass noun. You find examples of this when talking about academia. To wit:
There were two schools of architecture. There are five pieces of furniture. We will look at three branches of mathematics.
Clearly "mathematics" is like this, even though it is hiding as a regular plural noun in plain sight. The abbreviation is therefore more likely to be a matter for convention rather than following any set rule.
Math. therefore, is entirely logical as an abbreviation as indeed is the abbreviation Maths. Both are absolutely fine. Abbreviations don't necessarily need to follow the same set rules in their constriction (as if the English language bothered to follow rules anyway) and a select few even jump the divide in becoming legitimate words in their own right like "radar".
If this be the case then, then the discussion shouldn't be about whether or not "mathematics" is plural or singular and whether or not that should affect the abbreviation or not, but the whether the abbreviation can be mistaken for something else.
I had a look in the Macquarie Dictionary, the Oxford English Dictionary and a Merriam-Webster Dictionary and found that "math" is an archaic word which means "to be mowed" and only really finds any modern usage in the compound "aftermath". The word "polymath" means "one who has learned much" but that is derived from Greek and there is no need for that to be abbreviated.
The whole "math" or "maths" discussion then, purely comes down to a matter of style and national preference. If this is indeed the case, then the only questions to ask are "which came first?" and "who is responsible?". If it's Noah Webster who is responsible, then I'm already prejudiced against him (see Horse 505) and won't accept "math" out of sheer stubbornness. Since international organisations accept like the United Nations, the International Organization for Standardization and the World Trade Organization take the Oxford English Dictionary as their standard, then I see no reason why I shouldn't.
The OED doesn't even list "Math" as a word; therefore "Maths" wins.