In ECET 2026, Computer Organization & Architecture (COA) includes essential number system conversions that frequently appear in MCQs. One such high-scoring and easy topic is Binary to Decimal and Hexadecimal conversions. Mastering this topic ensures quick wins in the exam. This post includes a complete revision note, 10 handpicked MCQs, answer key, and explanations.
📘 Concept Notes – Binary to Decimal & Hexadecimal
🔢 1. Number Systems Overview:
- Binary (Base 2): Uses only 0 and 1. Example: 1011
- Decimal (Base 10): Common human number system. Example: 23
- Hexadecimal (Base 16): Uses 0-9 and A-F. Example: 1A3
🧮 2. Binary to Decimal Conversion:
Method:
Multiply each bit by 2 raised to its position (right to left) and add all values.
Example:
Convert 1011₂ → Decimal
= 1×2³ + 0×2² + 1×2¹ + 1×2⁰
= 8 + 0 + 2 + 1 = 11₁₀
🔁 3. Binary to Hexadecimal Conversion:
Method:
- Group binary digits in 4s from right.
- Convert each group to Hex equivalent.
Example:
Convert 10111110₂ → Hex
Group: 1011 1110
= B E → BE₁₆
Tip:
| Binary | Hex |
|---|---|
| 0000 | 0 |
| 0001 | 1 |
| 0010 | 2 |
| 0011 | 3 |
| 0100 | 4 |
| 0101 | 5 |
| 0110 | 6 |
| 0111 | 7 |
| 1000 | 8 |
| 1001 | 9 |
| 1010 | A |
| 1011 | B |
| 1100 | C |
| 1101 | D |
| 1110 | E |
| 1111 | F |
🔟 10 Most Expected MCQs – ECET 2026 [Binary to Decimal/Hex]
Q1. What is the decimal equivalent of 1001₂?
A) 7
B) 8
C) 9
D) 10
Q2. 1111₂ in decimal is:
A) 14
B) 15
C) 16
D) 17
Q3. What is the hexadecimal equivalent of 1010₂?
A) 8
B) 9
C) A
D) B
Q4. Convert 1101₂ to decimal.
A) 12
B) 13
C) 14
D) 15
Q5. What is the hex value of binary 1100 0101?
A) C1
B) C5
C) D5
D) A5
Q6. 100000₂ = ? in decimal
A) 16
B) 32
C) 64
D) 128
Q7. Which binary represents the hexadecimal number 2F?
A) 00101111
B) 10101111
C) 11110010
D) 11110000
Q8. 1110₂ in hex is:
A) A
B) D
C) E
D) F
Q9. Decimal 10 is equal to which binary?
A) 1010
B) 1110
C) 1100
D) 0111
Q10. What is the decimal value of 10000000₂?
A) 64
B) 128
C) 256
D) 512
✅ Answer Key Table
| Q.No | Answer |
|---|---|
| Q1 | C |
| Q2 | B |
| Q3 | C |
| Q4 | B |
| Q5 | B |
| Q6 | B |
| Q7 | A |
| Q8 | C |
| Q9 | A |
| Q10 | B |
🧠 Explanations of All Answers
- Q1 → C: 1001₂ = 1×2³ + 0×2² + 0×2¹ + 1×2⁰ = 9
- Q2 → B: 1111₂ = 8 + 4 + 2 + 1 = 15
- Q3 → C: 1010₂ = A₁₆
- Q4 → B: 1101₂ = 8 + 4 + 0 + 1 = 13
- Q5 → B: 1100 0101 → C5
- Q6 → B: 100000₂ = 2⁵ = 32
- Q7 → A: 2 = 0010, F = 1111 → 00101111
- Q8 → C: 1110₂ = E₁₆
- Q9 → A: Decimal 10 = 1010₂
- Q10 → B: 10000000₂ = 2⁷ = 128
🎯 Why This Practice Matters for ECET 2026
Number system conversion questions like Binary to Decimal and Hex are guaranteed entries in ECET. They are quick to solve, require no deep theory, and give you instant 1-mark advantage. Practicing these conversions helps in Digital Electronics, COA, and even Computer Programming modules.
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