Question 15
Use the digits 1,2,3,4,5,6 exactly once to form $\overline{abcdef}$. The full number is divisible by 6; $\overline{abcde}$ by 5; $\overline{abcd}$ by 4; $\overline{abc}$ by 3; and $\overline{ab}$ by 2. Find every possible six-digit number. Enter them in increasing order, separated by a comma.
There may be more than one valid number; give all of them rather than choosing just one.
There may be more than one valid number; give all of them rather than choosing just one.