AP CSA Unit 2 Day 28: Iteration Nested Loop Accumulation

February 6, 2026

Unit 2, Selection & Iteration • Cycle 2

Day 28 Advanced Practice • Harder Difficulty

Focus: Variable Inner Bound Hard Iteration (nested loop accumulation)

Advanced Practice Question

Format: Iteration (nested loop accumulation)

What is printed?

int sum = 0;
for (int i = 1; i <= 3; i++) {
    for (int j = 1; j <= 3; j++) {
        sum += i * j;
    }
}
System.out.println(sum);

Difficulty: Hard | Topic: Iteration (nested loop accumulation) | Cycle: 2 (Advanced)

Why This Answer?

x increments 1 time when i=1, 2 times when i=2, and 3 times when i=3. Total = 1+2+3 = 6.

Common Mistake

Watch Out!

Assuming inner loop always runs 3 times instead of depending on i.

AP Exam Strategy

When the inner bound depends on i, compute iterations for each i separately.

This Cycle 2 HARD question tests variable inner bound. Review Unit 2 concepts to build mastery of selection and iteration.

Cycle 2 questions prepare you for the hardest AP CSA exam questions.