Exam Sample Questions - Spring 2025

Below are sample questions along with explanations for each one. You can download the original file at the bottom of the page to try them out yourself! If you have any questions, please feel free to reach out or write a post in the community!

Q 1) Convert 32 into signed integer binary.

a) 1000 0000 0000 0000 0000 0000 0101 1001
b) 0000 0000 0000 0000 0000 0000 0010 0000
c) 0000 0000 0000 0000 0000 0000 0001 0000
d) 1000 0000 0000 0000 0000 0000 0010 0000
e) none of the above

Answer: b)

Explanation:

• In binary, decimal 32 is 100000 (that’s 2^5) in just 6 bits.

• But as a 32‐bit signed integer, we need 32 bits total. Leading zeros fill up the extra space, giving 0000 0000 0000 0000 0000 0000 0010 0000.

• 32 bits are required for a full signed int, so leading zeros are added to fill out the remaining bits.

Q 2) Convert 0000 0000 0000 0000 0000 0000 1100 0111 into integer decimal.

a) 123
b) 194
c) 199
d) 227
e) none of the above

Answer: c) 199

Explanation:

• Focus on the lower 8 bits: 1100 0111.

• Converting 1100 0111 to decimal:

  • (1 × 2^7) + (1 × 2^6) + (0 × 2^5) + (0 × 2^4) + (0 × 2^3) + (1 × 2^2) + (1 × 2^1) + (1 × 2^0)

  • = 128 + 64 + 0 + 0 + 0 + 4 + 2 + 1 = 199.

  
  

  Q 3) Convert 1100 0001 0100 0000 0000 0000 0000 0000 into floating‐point decimal.

  a) 35.0
  b) -200.0
  c) -12.0
  d) -24.0
  e) none of the above

  Answer: c) -12.0

  Explanation:

  • First bit = 1 → negative number

  • Exponent bits = 10000010 → decimal 130 → actual exponent is 130 - 127 = 3

  • Mantissa starts with an implied 1.0, followed by zeros → actual value is 1.5

  • So the number is: -1.5 × 2³ = -12.0
    That matches option (c).

  
  

  Q 4) Convert hexadecimal 2A into integer decimal.

  a) 21
  b) 35
  c) 42
  d) 68
  e) none of the above

  Answer: c) 42

  Explanation:

  • Hex 2A means (2 × 16) + (10) = 32 + 10 = 42.

  
  

  Q 5) Which expression is invalid (all variables are integers)?

  a) a + b - 0
  b) c % a % 4
  c) xm6 - 24
  d) xf3r6 + 2
  e) all are valid

  Answer: e) all are valid

  Explanation:

  • While xm6 and xf3r6 look unusual, in C you can name integer variables like that as long as they are declared properly (e.g., int xm6;).

  • The modulo chain in (b) is also valid if c % a yields some int, then % 4 again.

  • Subtraction by 0 or adding an integer is also valid.

  
  

  Q 6) Which expression is invalid?

  a) ant + int
  b) one + twx
  c) three * 3
  d) four / -4
  e) all are valid