6. (6 points) A two-digit number divides 723, the remainder is 30, there are $\qquad$ such two-digit numbers, which are $\qquad$ .


【Solution】Solution: $723-30=693$,
$693=3 \times 3 \times 7 \times 11$, so the two-digit divisors greater than 30 that can divide 723 are:
$11 \times 3=33$,
$11 \times 7=77$,
$3 \times 3 \times 7=63$,
$11 \times 3 \times 3=99$, a total of 4;
Therefore, the answer is: $33, 63, 77, 99$.