If you raise 9 to the 387th power, what is the units digit of the result

9*9  = 81 , 81*9 = 729, 729*9 =  8561, 8561 *9 =  59049  and so on
         9^2              9^3               9^4                      9^5

So the result of each multiplication is either 1 or 9 in the units digits

Even exponents give a 1 and odd give a 9  so  9^387  will have a units digit of 

9.

Where are the functions?