We need to make the greatest and the smallest 4-digit numbers using any four different digits with the conditions as given below:
Digit 7 is always at one’s place.
We know that,
9 > 8 > 7 > 6 > 5 > 4 > 3 > 2 > 1 > 0
So Clearly,
The greatest number would be:
9867
And, the smallest number would be:
1027