Programming concepts — GCSE Computer Science practice questions

Question 1

A gym gives each locker a 4-digit code, such as 0472. Codes are typed in and compared, but never used in calculations.

Which data type is most suitable for storing a locker code?

Accepted Answer

D: STRING. The code is several characters long, may start with 0 and is never used in arithmetic, so it should be stored as a STRING. As an INTEGER, 0472 would become 472; a CHAR holds only one character and a BOOLEAN only TRUE or FALSE.

Question 2

53 students go on a school trip. Each minibus has 12 seats. This pseudocode works out how many minibuses are completely full and how many students are left over.

```pseudocode
Students ← 53
Full ← DIV(Students, 12)
Left ← MOD(Students, 12)
OUTPUT Full, " ", Left
```

What is output?

Accepted Answer

A: 4 5. DIV(53, 12) is the whole-number part of 53 ÷ 12, which is 4. MOD(53, 12) is the remainder: 53 − 48 = 5. The output is 4 5.

Question 3

A puzzle game has a grid of 3 rows and 4 columns. A coin is placed on every square where the remainder of (Row + Col) divided by 3 is 0. This pseudocode counts the coins.

```pseudocode
Coins ← 0
FOR Row ← 1 TO 3
   FOR Col ← 1 TO 4
      IF MOD(Row + Col, 3) = 0
         THEN
            Coins ← Coins + 1
      ENDIF
   NEXT Col
NEXT Row
OUTPUT Coins
```

What is output?

Accepted Answer

B: 4. The IF runs for all 12 squares. Row + Col is a multiple of 3 for (1, 2), (2, 1), (2, 4) and (3, 3): Row + Col = 3, 3, 6, 6. So 4 coins are counted and 4 is output once, after both loops.