find how many 4 digits no. is less then 1239 such that all 4 digits are distinct.  Choose the correct answer.
A) 68 B) 69 C) 70 D) 71 E) 72
case 1- 1000-1099- there are 56 distinct digits   case 2- 1200-1209- there are 7 distinct digits   case 3- 1230-1239(excluding 1239)- there are 6 distinct digits   hence, 56+7+6=69   ANSWER:69
<result>B</result>
find how many 4 digits no. is less then 1239 such that all 4 digits are distinct.