Back to school
Your matematicianmathematician would have to learn math all over again, like a school child. Do recall that you are dropping him into a place where arabicArabic numerals have not yet been introduced, even less so the concept of "zero".
Sure, he can do his own math like a pro, but no-one else will be able to understand what he is doing because something as simple as $1 + 1 = 2$ is — well, I will not say "greek""Greek" ;) — incomprehensible to them.
So sure, he could, potetniallypotentially, revolutionize maths (once things like food, shelter, a job and communication is solved) simply by introducing new numbers and zero. The question is if others will join him in this entirely alien way of doing maths. And there are sure to be some very pertinent questions along the way, like "How the heck did you come up with all this?!".