Unit 1 Day 9: Integer Division & Modulo Practice
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Unit 1, Section 1.9
Day 9 Practice • January 15, 2026
🎯 Focus: Integer Division & Modulo
Practice Question
Consider the following code segment:
int a = 17;
int b = 5;
int result = a / b + a % b;
System.out.println(result);What is printed as a result of executing this code segment?
What This Tests: This question tests integer division (/) and the modulo operator (%). Both are frequently tested on the AP exam and are essential for understanding how Java handles integer arithmetic.
Key Concept: Integer Division vs Modulo
17 / 5 = 3 // Integer division: truncates decimal (not rounds!)
17 % 5 = 2 // Modulo: returns the remainder
// Think of it as: 17 = 5 × 3 + 2
// ↑ ↑
// (/) (%)Step-by-Step Trace
| Expression | Calculation | Result |
|---|---|---|
| a / b | 17 / 5 | 3 (truncated) |
| a % b | 17 % 5 | 2 (remainder) |
| result | 3 + 2 | 5 |
Common Mistakes
Mistake: Answer C (5.4)
Integer division does NOT produce decimals. When dividing two ints, the result is always an int. 17/5 = 3, not 3.4.
Mistake: Answer A (3)
This only accounts for a / b and forgets to add a % b.
Modulo Patterns
💡 Common Uses of Modulo
Check if even: n % 2 == 0
Check if odd: n % 2 == 1
Get last digit: n % 10
Wrap around: index % array.length
Related Topics
- Section 1.3: Arithmetic Operators
- Section 1.5: Type Casting
- Section 2.9: Using % in loops
Difficulty: Medium • Time: 1-2 minutes • AP Skill: 2.B - Determine output
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