Computer Science

50 Solved Number System Questions with Answers | CBSE Class 11 Computer Science

Class 11 · Computer Science

50 Solved Number System Questions with Answers (CBSE Class 11 Computer Science)

Number System is one of the most important chapters in Class 11 Computer Science. Regular practice is essential to master different types of number system conversions. This worksheet contains solved questions arranged from easy to advanced level.

Section A – Decimal to Binary (Easy)

Question	Answer
1. Convert 10₁₀ into Binary.	1010₂
2. Convert 15₁₀ into Binary.	1111₂
3. Convert 18₁₀ into Binary.	10010₂
4. Convert 25₁₀ into Binary.	11001₂
5. Convert 32₁₀ into Binary.	100000₂
6. Convert 45₁₀ into Binary.	101101₂
7. Convert 56₁₀ into Binary.	111000₂
8. Convert 75₁₀ into Binary.	1001011₂
9. Convert 99₁₀ into Binary.	1100011₂
10. Convert 100₁₀ into Binary.	1100100₂

Section B – Binary to Decimal

Question	Answer
11. 101₂	5₁₀
12. 111₂	7₁₀
13. 1001₂	9₁₀
14. 1010₂	10₁₀
15. 1111₂	15₁₀
16. 10010₂	18₁₀
17. 11001₂	25₁₀
18. 111000₂	56₁₀
19. 101101₂	45₁₀
20. 1100100₂	100₁₀

Section C – Decimal to Octal

Question	Answer
21. 25₁₀	31₈
22. 40₁₀	50₈
23. 64₁₀	100₈
24. 75₁₀	113₈
25. 125₁₀	175₈
26. 250₁₀	372₈
27. 512₁₀	1000₈
28. 600₁₀	1130₈
29. 725₁₀	1325₈
30. 999₁₀	1747₈

Section D – Decimal to Hexadecimal

Question	Answer
31. 26₁₀	1A₁₆
32. 45₁₀	2D₁₆
33. 64₁₀	40₁₆
34. 100₁₀	64₁₆
35. 125₁₀	7D₁₆
36. 255₁₀	FF₁₆
37. 512₁₀	200₁₆
38. 687₁₀	2AF₁₆
39. 999₁₀	3E7₁₆
40. 1024₁₀	400₁₆

Section E – Mixed Conversion Questions

Question	Answer
41. Convert 111001₂ to Octal.	71₈
42. Convert 357₈ to Binary.	011101111₂
43. Convert 11111111₂ to Hexadecimal.	FF₁₆
44. Convert 2AF₁₆ to Binary.	001010101111₂
45. Convert 725₈ to Hexadecimal.	1D5₁₆
46. Convert 3A₁₆ to Octal.	72₈
47. Convert 11110000₂ to Hexadecimal.	F0₁₆
48. Convert A5₁₆ to Binary.	10100101₂
49. Convert 100111₂ to Octal.	47₈
50. Convert 7B₁₆ to Decimal.	123₁₀

Quick Revision Tips

Binary → Group into 3 bits for Octal.
Binary → Group into 4 bits for Hexadecimal.
Decimal → Divide repeatedly by the base.
Remember A=10, B=11, C=12, D=13, E=14, F=15.
Always write the base as a subscript.

Challenge Yourself

Solve these without looking at the answers:

345₁₀ → Binary
101110101₂ → Decimal
755₈ → Hexadecimal
3FA₁₆ → Binary
100111101₂ → Octal