Math Help - congruents

1. congruents

$0^2= 0 (mod 8)$, $1^2= 1 (mod 8)$, $2^2= 4 (mod 8)$, $3^2= 9= 1 (mod 8)$, $4^2= 16= 0 (mod 8)$, $5^2= 25= 1 (mod 8)$, [tex] 6^2= 36= 4 (mod 8), and $7^2= 49= 1 (mod 8)$. Since every other number is congruent to one of those mod 8, you are done.