Arithmetic operators in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two numbers and print the result.

Java

int a = 5;
int b = 3;
int sum = a [1] b;
System.out.println(sum);

Drag options to blanks, or click blank then click option'

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' will subtract the numbers.

Using '*' or '/' will multiply or divide, not add.

The + operator adds two numbers together.

2fill in blank

medium

Complete the code to multiply two numbers and print the result.

Java

int x = 4;
int y = 7;
int product = x [1] y;
System.out.println(product);

Drag options to blanks, or click blank then click option'

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' will add instead of multiply.

Using '/' will divide instead of multiply.

The * operator multiplies two numbers.

3fill in blank

hard

Fix the error in the code to correctly divide two numbers and print the result.

Java

int numerator = 10;
int denominator = 2;
int result = numerator [1] denominator;
System.out.println(result);

Drag options to blanks, or click blank then click option'

A/

B-

C+

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' will subtract instead of divide.

Using '*' will multiply instead of divide.

The / operator divides the numerator by the denominator.

4fill in blank

hard

Fill both blanks to calculate the remainder of division and print it.

Java

int dividend = 17;
int divisor = 5;
int remainder = dividend [1] divisor;
System.out.println(remainder [2] 2);

Drag options to blanks, or click blank then click option'

A%

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '/' instead of '%' will give the quotient, not remainder.

Using '-' or '*' in the second blank will not add 2.

The % operator gives the remainder of division. The + operator adds 2 to the remainder.

5fill in blank

hard

Fill all three blanks to create a map of numbers to their squares for numbers greater than 3.

Java

Map<Integer, Integer> squares = new HashMap<>();
for (int num = 1; num <= 5; num++) {
    if (num [1] 3) {
        squares.put(num, num [2] num);
    }
}
System.out.println(squares[3]);

Drag options to blanks, or click blank then click option'

A>

B*

C.toString()

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' will filter wrong numbers.

Using '+' instead of '*' will not square the number.

Printing the map without converting to string may not show expected output.

The operator > checks if the number is greater than 3. The * operator squares the number. The .toString() method converts the map to a string for printing.

Practice

1. Which of the following is the correct symbol for the modulus operator in Java, which gives the remainder of a division?

easy

A. *

B. /

C. -

D. %

Solution

1. Step 1: Understand the modulus operator

   The modulus operator returns the remainder after division of two numbers.

2. Step 2: Identify the correct symbol in Java

   In Java, the symbol for modulus is %.

3. Final Answer:

   % -> Option D

4. Quick Check:

   Modulus operator = % [OK]

Hint: Modulus operator is always % in Java math [OK]

Common Mistakes:

• Confusing modulus % with division /
• Using * or - instead of %
• Thinking modulus returns quotient

2. Which of the following Java statements correctly calculates the product of two integers a and b?

easy

A. int result = a / b;

B. int result = a + b;

C. int result = a * b;

D. int result = a % b;

Solution

1. Step 1: Identify the multiplication operator

   In Java, the multiplication operator is *.

2. Step 2: Check the statement that uses multiplication

   The statement int result = a * b; correctly multiplies a and b.

3. Final Answer:

   int result = a * b; -> Option C

4. Quick Check:

   Multiplication operator = * [OK]

Hint: Use * for multiplication in Java expressions [OK]

Common Mistakes:

• Using + instead of * for multiplication
• Confusing division / with multiplication
• Using % which is remainder, not product

3. What is the output of the following Java code?

int x = 10;
int y = 3;
System.out.println(x / y);

medium

A. 3

B. 3.3333333

C. 3.0

D. 4

Solution

1. Step 1: Understand integer division in Java

   Both x and y are integers, so division drops the decimal part.

2. Step 2: Calculate integer division result

   10 divided by 3 is 3.333..., but integer division returns 3.

3. Final Answer:

   3 -> Option A

4. Quick Check:

   Integer division drops decimals = 3 [OK]

Hint: Integer division drops decimals, result is integer [OK]

Common Mistakes:

• Expecting decimal output with int division
• Confusing / with % operator
• Assuming automatic float conversion

4. Identify the error in the following Java code snippet:

int a = 5;
int b = 0;
int c = a / b;
System.out.println(c);

medium

A. Division by zero causes runtime error

B. Variable c is not declared

C. Missing semicolon after declaration

D. Incorrect use of modulus operator

Solution

1. Step 1: Analyze the division operation

   The code divides a by b, where b is zero.

2. Step 2: Understand division by zero in Java

   Dividing an integer by zero causes a runtime ArithmeticException error.

3. Final Answer:

   Division by zero causes runtime error -> Option A

4. Quick Check:

   Division by zero throws error [OK]

Hint: Never divide by zero; it crashes the program [OK]

Common Mistakes:

• Ignoring division by zero error
• Thinking it returns zero or infinity
• Confusing syntax error with runtime error

5. Given the code below, what will be the value of result after execution?

int a = 15;
int b = 4;
int result = a / b + a % b * 2;

hard

A. 11

B. 9

C. 8

D. 7

Solution

1. Step 1: Calculate integer division and modulus

   15 / 4 = 3 (integer division), 15 % 4 = 3 (remainder).

2. Step 2: Apply operator precedence and compute expression

   Expression is 3 + 3 * 2. Multiplication first: 3 * 2 = 6. Then addition: 3 + 6 = 9.

3. Step 3: Re-check calculation

   Wait, re-check: 15 / 4 = 3, 15 % 4 = 3, 3 * 2 = 6, 3 + 6 = 9.

4. Final Answer:

   9 -> Option B

5. Quick Check:

   Division + (modulus * 2) = 9 [OK]

Hint: Remember * before + in mixed expressions [OK]

Common Mistakes:

• Adding before multiplying
• Confusing division and modulus results
• Forgetting integer division truncates decimals