ITPEC FE Subject B April 2024 Question 3

Identifying even numbers using the modulo operator in pseudocode.

The program loops i from 1 to 100 and should output only even numbers, then print their sum. An even number satisfies the condition i mod 2 = 0 (remainder of division by 2 is zero).

Why not others:
- (a) `i ÷ 2 = 0` — integer division: i ÷ 2 equals 0 only when i is 0 or 1 (since 1 ÷ 2 = 0 in integer arithmetic). Does not test for evenness.
- (b) `i ÷ 2 ≠ 0` — true for almost all values of i (all except 0 and 1), so it would output nearly every number, not just evens.
- (d) `i mod 2 ≠ 0` — selects odd numbers (remainder is 1), the opposite of what is needed.
- (e) `i = 2` — only true once, so only the number 2 would be output.
- (f) `i ≠ 2` — true for every number except 2, outputting 1, 3, 4, 5, …, 100.

Key rule: x mod n = 0 checks divisibility — use it to filter multiples (even numbers = multiples of 2).

AI-generated — may contain errors