1/7 = 0.142857142857142857142857142857142857142857142857142857 and so on
the pattern repeats
the first digit is 1
second digit is 4
third digit is 2
fourth digit is 8
fifth digit is 5
sixth digit is 7
and then the seventh digit is 1, and it repeats
so the six digits repeat again and again...
2012/6 = 335 2/6
It has a remainder of 2, which means that the 12th digit will be 4. because that is the second digit. After going 335 times the 6 digit patterns it will stop at the second digit which is 4.
Your answer is 4.
I hope you understood, it was kind of hard to explain :P