The greatest 4-digit number with no repeated digits is... 9876
9876543
98,764
98765
987,654
The greatest 4-digit number with no repeated digits is... 9876
98,764
It is possible to create a 3-digit number, without repeated digits so the probability is 1.
9876543.
987654
98,764
9876543
98,764
98765
987,654
987653
757