Question

determinati ultima cifra a numarului 2 la puterea 2010

Answer 1

u($2^{1}$)= 2
u($2^{2}$)=4
u($2^{3}$)= 8
u($2^{4}$)=..6
u($2^{5}$)=..2
...

=> ca ultimele cifre se repeta in grupe de cate patru (2,4,8,6,...2,4,8,6)
=> 2010:4=502 rest 2 => u($2^{2010}$)=.4