Question 13
The smallest 4-digit number having three different digits is
(A) 1102
(B) 1012
(C) 1020
(D) 1002

For getting the smallest number, we write the digits in ascending order. The digits being 0,1 and 2.
Zero cannot be the first digit as it has no value and we need a 4 digit number. So, the smallest 4-digit number having three different digits is 1002.