Răspuns:
Explicație pas cu pas:
U(31^8) = U(1^8) = 1
_________
U(48^25) = U(8^25)
U(8^1) = 8
U(8^2) = 4
U(8^3) = 2
U(8^4) = 6
U(8^5) = 8
ultima cifra se repeta din 4 in 4
25 : 4 = 6 rest 1
U(48^25) = 8
____________
U(5^66) = 5
____________
U(44^90) = U(4^90)
U(4^1) = 4
U(4^2) = 6
U(4^3) = 4
U(44^90) = 6
_____________
U(29^19) = U(9^19)
U(9^1) = 9
U(9^2) = 1
U(9^3) = 9
U(29^19) = 9
_______________
U(7^1) = 7
U(7^2) = 9
U(7^3) = 3
U(7^4) = 1
U(7^5) = 7
ultima cifra se repeta din 4 in 4
109 : 4 = 27 rest 1
U(7^109) = 7