- 
					 If S= {2, 3, 4, 5, 7, 9} , then the number of different three-digit number (with all distinct digits) less than 400 that can be formed from S is ?
 
- 
                        
- 20
 - 40
 - 80
 - 120
 
 
Correct Option: A
The hundred place will be reserved for 3 or 2 
5 digits are free to fill rest  two places i,e., of tens and unit. 
Number of required 3 digit number = 2 x 5C2 = 20