Arithmetic
- Java course
- Beginner
- Lesson 24/116
- 4 min
Learn +, -, *, /, % operators.
Arithmetic operators
Java has five arithmetic operators: +, -, *, /, %. The first four do the usual four operations; % is the modulo (remainder) operator.
int a = 10;
int b = 3;
System.out.println(a + b); // 13
System.out.println(a / b); // 3 (integer division)
System.out.println(a % b); // 1 (remainder)Integer division gives an integer result: 10 / 3 = 3. For a decimal result, at least one side must be double: 10.0 / 3 = 3.333....
Integer vs decimal division
When you divide two ints, Java gives the result as an integer, dropping the fraction. For a decimal result, at least one side must be double.
System.out.println(7 / 2); // 3
System.out.println(7.0 / 2); // 3.5
System.out.println(7 / 2.0); // 3.5If one side of the division is double, Java automatically widens the other side to double too. This is widening conversion.
Knowing which type to use matters: double for averages, int for counting.
Practice Write arithmetic calculations
Write a Main class with a main method. Assign 20 to int a and 6 to int b. Print a + b, a / b and a % b on separate lines with println.
Sample solution
public class Main {
public static void main(String[] args) {
int a = 20;
int b = 6;
System.out.println(a + b);
System.out.println(a / b);
System.out.println(a % b);
}
}Expected output
26 3 2
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the result of 10 % 3?
- 10
- 3
- 0
- 1 Correct answer
Explanation: 10 % 3 = 1, because 10 = 3*3 + 1.
2 Complete the modulo operator
int remainder = 10 ____ 3;int remainder = 10 % 3;Explanation: 10 % 3 gives the remainder.
3 Match the operators
| Term | Meaning |
|---|---|
+ |
Addition |
- |
Subtraction |
* |
Multiplication |
% |
Remainder |