There's evidence for some elementary algebra in devising the Elvish calendar; in particular, they were aware that they couldn't quite fit the right number of days into a year, and devised leap days to compensate, and then compensated again for the deficiencies in that system:
Between yávië and quellë1 were inserted three enderi or 'middle-days'. This provided a year of 365 days which was supplemented by doubling the enderi (adding 3 days) in every twelfth year.
How any resulting inaccuracy was dealt with is uncertain. If the year was then of the same length as now, the yén2 would have been more than a day too long. That there was an inaccuracy is shown by a note in the Calendars of the Red Book to the effect that in the 'Reckoning of Rivendell' the last year of every third yén was shortened by three days: the doubling of the three enderi due in that year was omitted; 'but that has not happened in our time'.
Return of the King Appendix D: "The Calendars"
There's also some (limited) evidence for abstract mathematical thought, in that the Elves prefer a duodecimal number system; Tolkien remarks in Letter 344 that this is based on a simple mathematical observation:
The English use duodecimals and have special words for them, namely dozen and gross. The Babylonians used duodecimals. This is due to the elementary mathematical discovery, as soon as people stop counting on their fingers and toes, that 12 is a much more convenient number than 10.
The Letters of J.R.R. Tolkien 344: From a letter to Edmund Meskys. November 1972
As VBartilucci points out in a comment on the question, the advanced engineering seen among the Elves may hint at some practical mathematics, though I wouldn't want to come down on this definitively; based on Tolkien's intended themes, I would suggest that the Elves tend to prefer a more intuitionist approach to their craft, and of course one can't discount the presence of magic.
In any case, there's no evidence given of theoretical mathematics among the Elves.
1 Two of the seasons as reckoned in Rivendell; the words respectively translate to "autumn" and "fading", and between them basically correspond to what we would call autumn (possibly with some overlap with early winter)
2 "Long year", equivalent to 52,596 solar days