29. Find: (i) the smallest positive integer $d$ such that $7 \mid 2^{d}-1$;
(ii) the smallest positive integer $d$ such that $11 \mid 3^{d}-1$;
(iii) the smallest non-negative remainder and the absolute smallest remainder when $2^{d}$ is divided by 7;
(iv) the smallest non-negative remainder and the absolute smallest remainder when $3^{d}$ is divided by 11.
29. (i) 3 ;
(ii) 5 ;
(iii) $1,2,4 ; 1,2,-3$;
(iv) $1,3,9,5,4 ; 1,3,-2,5,4$.