1062 - Logic below
1062 contains 0,1,2,6 and on reordering 1062, we get...
0126 - O,1,2 are in series and are 3 numbers , so
3 * 2(last digit of series) = 6
so, we get 0126,
But we were still not happy, so we decided to interchange 1st two and last two no's
Therefore, we get
1062 --- Problem Solved....