Oh, dear, the children are fighting again. Just because someone speaks English in a different way doesn't make it wrong. It's just different. There are so many wrong ideas here that this is "time-out" time. All of you with strong ideas about something being wrong with "maths," or "math," go sit in a corner over there and put on the dunce caps.
English did not originate in England. It developed from the language of German and Danish barbarians in petty kingdoms in what is now England. The dialects are now called called Kentish, Mercian Northumbrian, and West Saxon. Harold, who lost the battle of Hastings to Bill the Bastard was undisputed ruler in only in the Earldom named for his father, Godwin. Some of the other earls paid homage to him, and some didn't.
http://etc.usf.edu/maps/pages/300/330/330.htm
The Scots language developed from the same source in the lowlands of what is now Scotland and is now considered by some to be a separate language.
English didn't really become a single unified language until the time of Edward I and continued from the beginning of his reign with many dialects. The numbering of Edward I emphasizes this since there were earlier Edwards (such as the Confessor) in the earlier kingdoms which became England. The concept of England espoused by Edward I encompassed Wales, Scotland and most of France. None of these dialects was more correct than the others. they are just different.
The concept of mathematics as a unified field of study was not widely known in medieval times when the seven liberal arts were divided into the trivium, grammar, logic, and rhetoric; and the quadrivium, arithmetic, geometry, music, and astronomy. There are elements of the modern concept of mathematics in both divisions.
Even though the subject may be divided into many separate areas, I do not believe that the word mathematics is plural. Calculus is not a mathematic. Neither are arithmetic, geometry (Euclidian, Non-Euclidian and others) algebra, differential equations, or any other special technical area such as numerical approximation. The suffix "ics" is often used to convey a sense of generality to many nouns such as gymnastics, optics, aeronautics, robotics, and many others. In that usage, the word is singular. In a word like statistics, the word might either be plural, speaking of various separate (a statistic) items, or singular as in the general idea. The suffix is also used in many English words in which the original noun is no longer in general use, such as numismatics, phonics, Ebonics and so on. On a similar subject, opera is the plural of opus, but it is seldom if ever used that way in English. The singular, datum, has two plurals in English, data and datums. Datums is used on the legend of maps where there are two levels from which levels are measured. A coastal map might have separate contour lines measured from mean sea level as well as high tide. Antenna also has two plurals. The ones on bugs are antennae and the electronic ones on an automobile, airplane or ship are antennas. Brits often avoid the issue and speak of aerials and earths instead of antennas and grounds.
Who won WWI and WWII? Certainly no single country. I believe the contribution of the US was more decisive in WWI because I think the Kaiser, Churchill and Haig were intent on killing all their opponents no matter how many casualties they incurred themselves. Ludendorff did the mathematics of attrition and decided to surrender after the entry of the Americans. Of course, he later decided that he had been stabbed in the back and supported Hitler. WWII was not quite so clear-cut. The RAF had defeated the Luftwaffe in 1940 with some US technical support and only minimum volunteer participation before the US entry in the war in December 1941. I think it might have been possible for the UK and Soviet Union to have defeated the Third Reich without the Americans, but it would have taken much longer. I think Admiral Yamamoto saw the situation properly.
On my travels to Russia, I often hear that the Russians won the war single-handed. They did suffer the most causalities and contributed greatly, but they didn't do it by themselves. When I travel to Europe, I make it a point to visit the various monuments and pay my respects. The eternal flame honoring "Those fallen for the Motherland" at the Kremlin wall in Aleksander's garden is an inspiring sight as are the monuments for hero cities.
http://mstecker.com/pages/rusmo4947-1.htm
The word "mathematics" is long, and it needs to be abbreviated. The Brit way is slightly longer and less efficient as in some other ways the Brits write. That doesn't make it wrong. It won't use one extra liter/litre of ink in ten years. The big problem in the US/UK thing is the word, "brew." If a Brit wants a cuppa tea and gets a beer, that's a disappointment. If a Yank wants a beer and gets a cuppa, that is too.
In other words, just because someone does it a different way doesn't make it wrong. It is just different and might even be better than the way you do it.
I am an engineer and have given lectures in optics and physics at two English universities, Cranfield and Cranwell. Optics is a part of physics and both are singular in both AE and BE. At that level, people do not usually fret over trivialities. The head of the physics department at Cranwell did comment (privately) on my use of "infinity," but engineers see it differently from physicists and mathematicians. Infinitely close is good enough "for all practical purposes."