10515 - Powers Et Al.

http://mathcentral.uregina.ca/QQ/database/QQ.09.04/landon1.html

http://khvmathematics.blogspot.com/2008/01/how-to-find-last-digit-of-any-number.html

(1) Divide n by 4

(2) If the remainder is r, then the last digit is ((m%10)^r)%10. 

(3) if the remainder is zero, set r=4 and do (2).