Octal and hexadecimal conversion: Class 11 practice
Group binary digits in threes (from the right) for octal and in fours for hexadecimal. Read the method, follow the three worked examples, then try the six questions.
What you should know first
- Binary conversion
The idea behind octal and hexadecimal conversion
Group binary digits in threes (from the right) for octal and in fours for hexadecimal. Hex digits run 0–9 then A–F (10–15).
Step-by-step method
- Write the binary form.
- Group in 3s (octal) or 4s (hex) from the right.
- Replace each group by its digit.
Worked example 1 (Basic)
Convert 3173 to octal.
- Binary 110001100101
- Group in 3s → (6145)₈
- Answer: (6145)₈
Worked example 2 (Standard)
Convert 2564 to hexadecimal.
- Binary 101000000100
- Group in 4s → (A04)₁₆
- Answer: (A04)₁₆
Worked example 3 (Challenge)
Convert (AFD)₁₆ to octal.
- Hex → binary 101011111101
- Group in 3s → (5375)₈
- Answer: (5375)₈
Common mistakes and misconceptions
- Grouping from the left
- Writing 10 instead of A in hex
Practice questions
- (Basic) Convert 1504 to octal.
- (Basic) Convert 1434 to octal.
- (Standard) Convert 2839 to hexadecimal.
- (Standard) Convert 1897 to hexadecimal.
- (Challenge) Convert (272)₁₆ to octal.
- (Challenge) Convert (638)₁₆ to octal.
Answer key with full working
- Q1: Binary 10111100000 → Group in 3s → (2740)₈ → Answer: (2740)₈
- Q2: Binary 10110011010 → Group in 3s → (2632)₈ → Answer: (2632)₈
- Q3: Binary 101100010111 → Group in 4s → (B17)₁₆ → Answer: (B17)₁₆
- Q4: Binary 11101101001 → Group in 4s → (769)₁₆ → Answer: (769)₁₆
- Q5: Hex → binary 1001110010 → Group in 3s → (1162)₈ → Answer: (1162)₈
- Q6: Hex → binary 11000111000 → Group in 3s → (3070)₈ → Answer: (3070)₈
Syllabus note
This skill is listed under "Computer Systems and Organisation" for Class 11 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.
Related practice and notes
Frequently asked questions
Which chapter is octal and hexadecimal conversion in?
"Computer Systems and Organisation", Class 11 Computer Science (NCERT/CBSE). Other boards may place it differently.
How were the answers checked?
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.