750
The greatest 9-digit number using three different digits is 999888777, formed by using the digits 9, 8, and 7 in descending order. The smallest 9-digit number using three different digits is 100000000, created with the digits 1, 0, and 0. This arrangement ensures that the number starts with 1, followed by the zeros to maintain the smallest value.
102 is the smallest three digit number with different digits.
000
100122 or, if negative numbers are permitted, -998877
638
102
smallest 8 digit number with three different digits
-4309278
161226
102
10002
100,002.