GCSE (9-1) Computer Science
Mark Scheme
J277/02: Data Types & Casting
Question Answer Marks Guidance
1a 9 1
Examiner's Note: GHOST TOPIC. Students routinely write '10'. Zero marks for '10'. They must understand that int() floors the value.
1b Casting to an integer truncates (removes) the decimal part; it does not round up. 1
2 Row 1 Values:
  • val1: 65 (1)
  • val2: 67 (1)
  • char2: 'C' (1)
  • Output: 'C' (1)
 4
Examiner's Note: GHOST TOPIC. This relies on 2.2.3 (string/char manipulation) and explicitly uses the ASC/CHR commands listed in the specification.
3
  • "15" (String) (1)
  • 17 (Integer) (1)
  • 4.0 (Real/Float) (1)
 3
Part 3 is the discriminator. int(4.8) becomes 4. float(4) becomes 4.0.
4a Explanation that a non-empty string (even "False") is "truthy" in many languages/Python, so bool("False") becomes True.
OR: It casts the presence of text, not the meaning of the text. 		2
Examiner's Note: GHOST TOPIC. Explicit boolean casting is rare in exams but critical for "Robust Programs".
4b if userInput == "False": isValid = False
(or similar logic). 		2
5 num = random(65, 90)
letter = CHR(num)
print(letter) 		3
1 mark for random range.
1 mark for CHR cast.
1 mark for print.
6a Line 03 1
6b print("You are " + str(ageMonths) + " months old.") 2
Must cast ageMonths to String.
1 mark for str(), 1 mark for correct syntax.
7
  • Gap 1: float (or real) (1)
  • Gap 2: str (or String) (1)
 3
int is not accepted for the first gap because the prompt specified "decimal number".
8 102 2
Concatenation, not addition. 1 mark for 102. 0 marks for 12.
9 It removes the fractional part of the number (precision), making the data less accurate. 2
Must refer to "loss of precision" or "decimal part removed".
OCR 2026