The smallest 4 digit number with different digits is _______________
Answer : 1023
the smallest digit, other than 0, at thousand place to make smallest 4 digit number is 1.
As 1 is already used, smallest digit (0) can be used at hundred place.
similarly we can place 2 at tenth position and 3 at unit position.
So, smallest 4 digit number is 1023.