The pre-Columbian Maya people were good at math.
Why were they good at math?
They had two calendars: One, the Haab’, was roughly equivalent to our 365-day solar calendar. The other, the Tzolk’in (or Sacred Round), was a 260-day calendar delineating the spiritual year.
According to one textbook, anyway, they developed advanced math skills in the process of trying to synchronize their two calendars.
Side note: Why 260 days? Read the fascinating theories in wikipedia under the heading Origin of the Tzolk’in.