Digital Electoronics Kerala PSC Computer science repeating question

1. One's Compliment of 1001 is :
 Question from Instructor VHSE 2015
 Ans is :0110
Explanation: For Ones Complement replace 1's into 0 and 0's into 1's
2. In hexadecimal number system , 'E'  stands for .
 Question from Instructor VHSE 2015
 Ans is :14
Explanation: A=10,B=11,C=12,D=13,E=14.
 3. The last number in octal number system is
 Question from Instructor VHSE 2015
 Ans is :7
4. The binary number corressponding to 5
 Question from Instructor VHSE 2015
Ans is :101
Explanation:
000=0

001=1

010 =2

011=3

100=4

101=5
5. 654(8) is a number in                                        number system 
  Question from Instructor VHSE 2015
Ans is :Octal