Determinam intai ultima cifra a puterii [tex]2013^{2012}=(2013^4)^{504}=\overline{...1}^{504}=\overline{...1}
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[tex]u(5x^2)\in\{0,5\}[/tex]
[tex]u(3y^2)\in\{0,6\}[/tex](Fals deoarece y² poate avea ultima cifra 0,1,4,9,6,5=> 3y² are ultima cifra 0,3,2,7,8,5)
