Simon Whistler of Today I Found Out ponders why British English uses the plural term “maths” while American English uses the singular term “math” and how that came to be. While the short answer is that the difference is due to the accepted lexicon, the longer answer explains why both cases are considered to be correct.
Unsurprisingly, for no known reason, even though both were used on either side of the pond for a time, the “math” version of the abbreviation ended up being more popular than its plural-sounding “maths” in the United States, whereas eventually the opposite was true in the UK.
Whistler surmises that the additional “s” on the British version had to do with how academia referenced subjects.
While there is some debate here, this seems to have come about owing to a common convention around the time mathematics popped into English where it was en vogue to use a plural name for different fields of study, such as economics, linguistics, physics, acoustics, etc.
Yet the American version relies on the fact that the word “mathematics” is not actually plural.
But unfortunately for the “mathematics is plural” crowd, other than a few isolated instances in very recent times (likely stemming from the misconception that mathematics is plural), it’s long been the case that mathematics has been almost universally treated as singular in common usage.
As stated above, neither is right nor wrong, they just are.
But at the end of the day, both math and maths are just abbreviations for mathematics that turned into proper words, with some choosing to go with the contracted version of the abbreviation instead of the shorter “math” and it just sort of catching on one way or the other from there.