Arithmetic operators in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

C++

#include <iostream>

int main() {
    int a = 5, b = 3;
    int sum = a [1] b;
    std::cout << sum << std::endl;
    return 0;
}

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus - instead of plus +.

Using multiplication * or division / by mistake.

The plus sign + adds two numbers together.

2fill in blank

medium

Complete the code to calculate the remainder of division.

C++

#include <iostream>

int main() {
    int x = 10, y = 3;
    int remainder = x [1] y;
    std::cout << remainder << std::endl;
    return 0;
}

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

A/

B+

C%

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using division / instead of remainder %.

Using multiplication * or addition + by mistake.

The percent sign % gives the remainder after division.

3fill in blank

hard

Fix the error in the code to multiply two numbers correctly.

C++

#include <iostream>

int main() {
    int a = 4, b = 7;
    int product = a [1] b;
    std::cout << product << std::endl;
    return 0;
}

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

A*

B/

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using plus + or minus - instead of multiplication.

Using division / by mistake.

The asterisk * is the multiplication operator in C++.

4fill in blank

hard

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

C++

#include <iostream>
#include <map>

int main() {
    std::map<int, int> squares;
    for (int num = 1; num <= 5; ++num) {
        if (num [1] 3) {
            squares[num] = num [2] num;
        }
    }
    for (const auto& [key, value] : squares) {
        std::cout << key << ": " << value << std::endl;
    }
    return 0;
}

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

A>

B<

C**

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than < instead of greater than >.

Using ** which is not a valid operator in C++.

The condition num > 3 selects numbers greater than 3. The multiplication operator * squares the number.

5fill in blank

hard

Fill all three blanks to create a map of uppercase letters to their ASCII codes for letters with codes greater than 65.

C++

#include <iostream>
#include <map>
#include <cctype>

int main() {
    std::map<char, int> letter_codes;
    for (char ch = 'A'; ch <= 'E'; ++ch) {
        if (static_cast<int>(ch) [1] 65) {
            letter_codes[[2]] = static_cast<int>([3]);
        }
    }
    for (const auto& [letter, code] : letter_codes) {
        std::cout << letter << ": " << code << std::endl;
    }
    return 0;
}

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

A>

Bch

Ctoupper(ch)

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than < instead of greater than >.

Using lowercase ch as value without conversion.

The condition ch > 65 checks ASCII codes greater than 65. The key uses ch and the value uses toupper(ch) to ensure uppercase letters.

Practice

1. Which arithmetic operator in C++ is used to find the remainder of a division?

easy

A. -

B. /

C. %

D. *

Solution

1. Step 1: Understand the meaning of each operator

   The operator % returns the remainder after division, while / returns the quotient.

2. Step 2: Identify the operator for remainder

   Since remainder is asked, the correct operator is %.

3. Final Answer:

   % -> Option C

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remainder uses % symbol, not division / [OK]

Common Mistakes:

• Confusing / with %
• Using * for remainder
• Using - for remainder

2. Which of the following is the correct syntax to multiply two integers a and b in C++?

easy

A. a * b;

B. a x b;

C. a multiply b;

D. a . b;

Solution

1. Step 1: Recall multiplication operator syntax

   In C++, multiplication uses the asterisk symbol * between operands.

2. Step 2: Check each option

   Only a * b; uses the correct operator and syntax.

3. Final Answer:

   a * b; -> Option A

4. Quick Check:

   Multiplication operator = * [OK]

Hint: Use * for multiplication, not words or symbols [OK]

Common Mistakes:

• Using x instead of *
• Writing multiply as word
• Using dot operator for math

3. What is the output of the following C++ code?

int a = 10, b = 3;
std::cout << a / b << std::endl;

medium

A. 3.33333

B. 3

C. 4

D. Error

Solution

1. Step 1: Understand integer division in C++

   Both a and b are integers, so division truncates decimals.

2. Step 2: Calculate integer division result

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

3. Final Answer:

   3 -> Option B

4. Quick Check:

   Integer division truncates decimals = 3 [OK]

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

Common Mistakes:

• Expecting decimal result
• Using floating-point division without casting
• Thinking output is error

4. Identify the error in this C++ code snippet:

int x = 5;
int y = 2;
int z = x / y.0;
std::cout << z << std::endl;

medium

A. Syntax error due to decimal point in divisor

B. Using floating-point literal with integer division

C. Incorrect variable declaration

D. Missing semicolon

Solution

1. Step 1: Analyze the divisor y.0

   The expression y.0 is invalid syntax in C++ because variables cannot have decimal points.

2. Step 2: Identify the syntax error

   The decimal point after y causes a syntax error; correct would be y * 1.0 or static_cast<double>(y).

3. Final Answer:

   Syntax error due to decimal point in divisor -> Option A

4. Quick Check:

   Variable names cannot have decimal points [OK]

Hint: Variable names can't have dots; causes syntax error [OK]

Common Mistakes:

• Thinking y.0 is valid float
• Ignoring syntax error
• Confusing variable and literal

5. Given int a = 7, b = 4;, which expression correctly calculates the average as a floating-point number in C++?

hard

A. a / b + 2

B. (a + b) / 2

C. a + b / 2

D. (a + b) / 2.0

Solution

1. Step 1: Understand integer vs floating-point division

   Using 2 divides integers, truncating decimals. Using 2.0 forces floating-point division.

2. Step 2: Evaluate each option

   (a + b) / 2 does integer division, result 5. (a + b) / 2.0 divides by 2.0, giving 5.5 as float. Options C and D do not calculate average correctly.

3. Final Answer:

   (a + b) / 2.0 -> Option D

4. Quick Check:

   Use floating-point divisor for decimal average [OK]

Hint: Divide by 2.0 to get decimal average, not integer [OK]

Common Mistakes:

• Using integer 2 causing truncation
• Wrong operator precedence
• Misinterpreting average formula