The successor of largest four digit number using each of the digits 7, 1, 0, 5 only once is
5017
7511
7501
1057
The largest four digit number using each of the digits 7, 1, 0, 5 only once is 7510. Its successor is 7510 + 1 = 7511
The predecessor of smallest four digit number made using each of the digits 6, 2, 0, 8 only once is
Write the largest 3 digit number with the digits 0,1 and 3 each digit being used only once.