ใช้modคับ
$2 \equiv 2 \pmod{7}$
$ 2^3 =8 , 8 \equiv 1 \pmod{7} $
$ \because (2^3)^{669} = 2^{2007}$
$ \therefore 2^{2007} \equiv 1 \pmod{7}$
$ 2^{2007} \times 2 \equiv 2 \pmod{7}$
$---------------------------$
$ 2008 \equiv 6 \pmod{7}$
$ 2008^2 \equiv 36$
$\equiv 1 \pmod{7}$
$---------------------------$
$\therefore 2^{2008} + 2008^2 \equiv 2+1 \pmod{7}$
$ \equiv 3 \pmod{7}$
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Just SIX......
and Seven......
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