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Number Systems & Logic MCQs 2026

45 questions with detailed answers · 18 from past papers · 5 quiz batches available

📚 Computer Mcqs 📄 18 Past-Paper Qs ✓ Free · No Login Needed
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Read each question, think about the answer, then click Show Answer to reveal the correct option and explanation. Load 10 at a time so it stays manageable — perfect for one-topic study sessions on the bus or during a break.

Page 1 of 1 Questions 1–10 of 45
  1. Q1 medium

    The hexadecimal number system is often used because it is

    1. A Slower
    2. B A shorthand for binary
    3. C Base 10
    4. D Only for text
    💡 Explanation:

    Hexadecimal is a compact shorthand for representing binary values.

  2. Q2 medium

    The decimal number 10 in hexadecimal is

    1. A A
    2. B 10
    3. C F
    4. D B
    💡 Explanation:

    Decimal 10 equals A in hexadecimal.

  3. Q3 medium

    The binary number 1111 equals which decimal number

    1. A 7
    2. B 8
    3. C 14
    4. D 15
    💡 Explanation:

    Binary 1111 equals 8+4+2+1 = 15 in decimal.

  4. Q4 medium

    The octal number 10 equals which decimal number

    1. A 2
    2. B 10
    3. C 8
    4. D 16
    💡 Explanation:

    Octal 10 equals decimal 8.

  5. Q5 medium

    The base of a number system is also called its

    1. A Digit
    2. B Radix
    3. C Bit
    4. D Nibble
    💡 Explanation:

    The base of a number system is also known as its radix.

  6. Q6 easy

    The decimal number 4 in binary is

    1. A 100
    2. B 010
    3. C 110
    4. D 011
    💡 Explanation:

    Decimal 4 equals 100 in binary.

  7. Q7 medium

    A NAND gate is an AND gate followed by a

    1. A OR gate
    2. B XOR gate
    3. C Buffer
    4. D NOT gate
    💡 Explanation:

    A NAND gate is an AND gate whose output is inverted by a NOT gate.

  8. Q8 medium

    The hexadecimal digit C represents which decimal value

    1. A 10
    2. B 11
    3. C 12
    4. D 13
    💡 Explanation:

    In hexadecimal, C equals decimal 12.

  9. Q9 easy

    Which number system is most convenient for humans in daily life

    1. A Binary
    2. B Decimal
    3. C Octal
    4. D Hexadecimal
    💡 Explanation:

    The decimal system is the most convenient for everyday human use.

  10. Q10 medium

    The output of an XOR gate when both inputs are 1 is

    1. A 0
    2. B 1
    3. C Undefined
    4. D High
    💡 Explanation:

    An XOR gate outputs 0 when both inputs are equal (1 and 1).

  11. Q11 easy

    Which of the following is NOT a valid binary digit

    1. A 0
    2. B 1
    3. C Both 0 and 1 are valid
    4. D 2
    💡 Explanation:

    2 is not a valid binary digit; binary uses only 0 and 1.

  12. Q12 easy

    The number of bits in a nibble is

    1. A 2
    2. B 8
    3. C 4
    4. D 16
    💡 Explanation:

    A nibble consists of 4 bits.

  13. Q13 medium

    Which gate is known as the inverted OR gate

    1. A AND
    2. B XOR
    3. C NAND
    4. D NOR
    💡 Explanation:

    A NOR gate is an OR gate with an inverted output.

  14. Q14 Past Paper · PPSC/FPSC/NTS easy

    The hexadecimal number system has a base of

    1. A 2
    2. B 8
    3. C 10
    4. D 16
    💡 Explanation:

    The hexadecimal number system uses base 16.

  15. Q15 Past Paper · PPSC/FPSC/NTS easy

    The octal number system has a base of

    1. A 8
    2. B 2
    3. C 10
    4. D 16
    💡 Explanation:

    The octal number system uses base 8 (digits 0 to 7).

  16. Q16 Past Paper · PPSC/FPSC/NTS easy

    The decimal number system has a base of

    1. A 2
    2. B 8
    3. C 10
    4. D 16
    💡 Explanation:

    The decimal number system uses base 10.

  17. Q17 easy

    How many digits are used in the binary system

    1. A 1
    2. B 2
    3. C 8
    4. D 10
    💡 Explanation:

    Binary uses only two digits: 0 and 1.

  18. Q18 medium

    Which digits are used in the octal number system

    1. A 0-9
    2. B 0 and 1
    3. C 0-F
    4. D 0-7
    💡 Explanation:

    Octal uses the digits 0 through 7.

  19. Q19 Past Paper · PPSC/FPSC/NTS medium

    In hexadecimal, the letter A represents the decimal value

    1. A 10
    2. B 11
    3. C 12
    4. D 15
    💡 Explanation:

    In hexadecimal, A equals decimal 10.

  20. Q20 Past Paper · PPSC/FPSC/NTS medium

    In hexadecimal, the letter F represents the decimal value

    1. A 10
    2. B 13
    3. C 15
    4. D 16
    💡 Explanation:

    In hexadecimal, F equals decimal 15.

  21. Q21 easy

    The decimal number 2 in binary is

    1. A 01
    2. B 10
    3. C 11
    4. D 00
    💡 Explanation:

    Decimal 2 is written as 10 in binary.

  22. Q22 medium

    The decimal number 5 in binary is

    1. A 100
    2. B 110
    3. C 111
    4. D 101
    💡 Explanation:

    Decimal 5 equals 101 in binary (4+1).

  23. Q23 medium

    The decimal number 8 in binary is

    1. A 1000
    2. B 1010
    3. C 1100
    4. D 0100
    💡 Explanation:

    Decimal 8 equals 1000 in binary.

  24. Q24 Past Paper · PPSC/FPSC/NTS medium

    The binary number 1010 equals which decimal number

    1. A 8
    2. B 12
    3. C 10
    4. D 6
    💡 Explanation:

    Binary 1010 equals 8+0+2+0 = 10 in decimal.

  25. Q25 medium

    The binary number 111 equals which decimal number

    1. A 5
    2. B 7
    3. C 6
    4. D 8
    💡 Explanation:

    Binary 111 equals 4+2+1 = 7 in decimal.

  26. Q26 Past Paper · PPSC/FPSC/NTS hard

    The decimal number 255 in binary is

    1. A 11110000
    2. B 10000000
    3. C 11111110
    4. D 11111111
    💡 Explanation:

    Decimal 255 equals 11111111 in binary (eight 1s).

  27. Q27 Past Paper · PPSC/FPSC/NTS easy

    A binary digit is also called a

    1. A Bit
    2. B Byte
    3. C Nibble
    4. D Word
    💡 Explanation:

    A binary digit (0 or 1) is called a bit.

  28. Q28 medium

    The rightmost bit in a binary number is called the

    1. A MSB
    2. B Parity bit
    3. C LSB
    4. D Sign bit
    💡 Explanation:

    The rightmost bit is the Least Significant Bit (LSB).

  29. Q29 medium

    The leftmost bit in a binary number is called the

    1. A LSB
    2. B MSB
    3. C Carry bit
    4. D Stop bit
    💡 Explanation:

    The leftmost bit is the Most Significant Bit (MSB).

  30. Q30 Past Paper · PPSC/FPSC/NTS medium

    In binary addition, 1 + 1 equals

    1. A 1
    2. B 11
    3. C 100
    4. D 10
    💡 Explanation:

    In binary, 1 + 1 equals 10 (0 with a carry of 1).

  31. Q31 Past Paper · PPSC/FPSC/NTS medium

    A logic gate that outputs 1 only when all inputs are 1 is the

    1. A AND gate
    2. B OR gate
    3. C NOT gate
    4. D XOR gate
    💡 Explanation:

    An AND gate outputs 1 only when all of its inputs are 1.

  32. Q32 Past Paper · PPSC/FPSC/NTS medium

    A logic gate that outputs 1 when at least one input is 1 is the

    1. A AND gate
    2. B NOT gate
    3. C OR gate
    4. D NAND gate
    💡 Explanation:

    An OR gate outputs 1 when at least one input is 1.

  33. Q33 Past Paper · PPSC/FPSC/NTS medium

    A logic gate that reverses or inverts its input is the

    1. A AND gate
    2. B NOT gate
    3. C OR gate
    4. D XOR gate
    💡 Explanation:

    A NOT gate inverts its single input.

  34. Q34 medium

    A logic gate that outputs 1 only when its inputs are different is the

    1. A AND gate
    2. B OR gate
    3. C NOT gate
    4. D XOR gate
    💡 Explanation:

    An XOR gate outputs 1 only when its inputs differ.

  35. Q35 medium

    The NOT gate is also called a/an

    1. A Inverter
    2. B Buffer
    3. C Adder
    4. D Comparator
    💡 Explanation:

    A NOT gate is also known as an inverter.

  36. Q36 Past Paper · PPSC/FPSC/NTS medium

    Which of the following is called a universal gate

    1. A AND
    2. B OR
    3. C NAND
    4. D XOR
    💡 Explanation:

    NAND (and NOR) are universal gates that can build any other gate.

  37. Q37 easy

    How many inputs does a basic NOT gate have

    1. A 2
    2. B 1
    3. C 3
    4. D 4
    💡 Explanation:

    A basic NOT gate has a single input.

  38. Q38 medium

    The AND gate output is 0 when

    1. A Both inputs are 1
    2. B Both inputs are high
    3. C One input is 1
    4. D At least one input is 0
    💡 Explanation:

    An AND gate outputs 0 whenever at least one input is 0.

  39. Q39 medium

    The OR gate output is 0 only when

    1. A All inputs are 0
    2. B All inputs are 1
    3. C One input is 1
    4. D Inputs are different
    💡 Explanation:

    An OR gate outputs 0 only when all inputs are 0.

  40. Q40 Past Paper · PPSC/FPSC/NTS medium

    ASCII stands for

    1. A American Standard Communication Interface
    2. B Advanced Standard Code
    3. C American Standard Code for Information Interchange
    4. D Automatic Standard Code Interface
    💡 Explanation:

    ASCII stands for American Standard Code for Information Interchange.

  41. Q41 Past Paper · PPSC/FPSC/NTS medium

    Standard ASCII uses how many bits to represent a character

    1. A 8
    2. B 7
    3. C 16
    4. D 4
    💡 Explanation:

    Standard ASCII uses 7 bits per character.

  42. Q42 Past Paper · PPSC/FPSC/NTS medium

    How many characters can standard 7-bit ASCII represent

    1. A 64
    2. B 256
    3. C 512
    4. D 128
    💡 Explanation:

    7-bit ASCII can represent 2^7 = 128 characters.

  43. Q43 Past Paper · PPSC/FPSC/NTS medium

    Boolean algebra was developed by

    1. A Charles Babbage
    2. B Alan Turing
    3. C George Boole
    4. D John Napier
    💡 Explanation:

    George Boole developed Boolean algebra, the basis of digital logic.

  44. Q44 medium

    BCD stands for

    1. A Binary Coded Decimal
    2. B Basic Coded Digit
    3. C Binary Computer Data
    4. D Byte Coded Decimal
    💡 Explanation:

    BCD stands for Binary Coded Decimal.

  45. Q45 Past Paper · PPSC/FPSC/NTS easy

    The binary number system has a base of

    1. A 8
    2. B 2
    3. C 10
    4. D 16
    💡 Explanation:

    The binary number system uses base 2 (digits 0 and 1).

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