Question

Ma ajutați va rog?
Afla ultima cifra nr:
11 la puterea 2009 + 15 la puterea 2009 + 16 la puterea 2009

Answer 1

$u( 11^{2009} )=u( 1^{2009})=u(1)$
$u( 15^{2009})=u( 5^{2009})=u(5)$
$u( 16^{2009} )=u( 6^{2009})-u(6)$
$u(1)+u(5)+u(6)=u(2)$