maths (n.)

"the science of quantity; the abstract science which investigates the concepts of numerical and spatial relations," 1580s; see mathematic (the older form of the word in English, attested from late 14c.) + -ics. Originally one of three branches of Aristotelian theoretical science, along with first philosophy (or metaphysics) and physics (or natural philosophy).

Mystical doctrines as to the relation of time to eternity are also reinforced by pure mathematics, for mathematical objects, such as numbers, if real at all, are eternal and not in time. Such eternal objects can be conceived as God's thoughts. [Bertrand Russell, "A History of Western Philosophy"]

American English shortening of mathematics, 1890; the British preference, maths, is attested from 1911. "Math. is used as an abbreviation in written English in the U.K. but not in speech, the normal form being Maths" [OED].