13^27 mod 55 = (13^3)^9 mod 55 = 52^9 mod 55 13^3 mod 55 =52 52^9=(52^2)^4*52 52^2 mod 55=9 9^4*52 mod 55 =7 13^27 mod 55 =7 11^27 = (11^3)^9 mod 55 11^3 mod 55 =11 11^9 mod 55 11^2 mod 55 =11 11^5 mod 55 = 11^2 mod 55 = 11