u.c. =("not" deasupra, adica notatie) ultima cifra
2^{1002} = u.c. 4 <= 2|1002 6|1002 ( | = divide )
15^{200} = u.c. 5 <= u.c.5 ^{n} = u.c. 5
6^{107} = u.c. 6 <= 6^{n} = u.c. 6
5^{1005} = u.c. 5 <= 5^{n} = u.c. 5
4^{200} = u.c. 6 <= 4^{2n} = u.c. 6; (unde 2n=nr par)
4^{201} = u.c 4 <= 4^{2n+1} = u.c. 4 (unde 2n+1=nr impar)
2001^{1000} = u.c.1 <= u.c. 1^{n} = u.c. 1 sau regula 1^{n} = 1