I believe it is:
987,654
9876543
9876543
987654321
The smallest positive integer six-digit number is 100000.
0
987
9876543
9876543
987654321
9,876,543
Multiples of 12 are even. Start with 999998. It's not divisible by 12. Try 999996. It is divisible by 12. Stop there.
The smallest positive integer six-digit number is 100000.
The greatest possible number is 888... (repeating).
0
5, or .8 with a three repeating.
Since we want our number to be as large as possible, we have to put the largest digits in the front, in the largest places so they have more value. Therefore, our answer would be 987,654,321.
1,023,456,789