Arithmetic operators in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of mixed arithmetic operations

What is the output of this Python code?

Python

result = 10 + 4 * 3 - 6 / 2
print(result)

A 19.0

B 22.0

C 20.0

D 18.0

💡 Hint

Remember the order of operations: multiplication and division happen before addition and subtraction.

Multiplication and division are done first: 4*3=12 and 6/2=3. Then addition and subtraction: 10 + 12 - 3 = 19.0

❓ Predict Output

intermediate

Integer division and modulo output

What will be printed by this code?

Python

a = 17
b = 5
print(a // b, a % b)

A 2 3

B 3 3

C 2 2

D 3 2

💡 Hint

Integer division (//) gives the quotient without remainder, modulo (%) gives the remainder.

17 divided by 5 is 3 with remainder 2, so output is '3 2'.

❓ Predict Output

advanced

Result of chained arithmetic with parentheses

What is the output of this code snippet?

Python

value = (8 + 2) * (5 - 3) ** 2 / 2
print(value)

A 40.0

B 20.0

C 100.0

D 50.0

💡 Hint

Calculate inside parentheses first, then exponentiation, then multiplication and division.

Inside parentheses: (8+2)=10 and (5-3)=2. Exponentiation: 2**2=4. Then multiply: 10*4=40. Finally divide by 2: 40/2=20.0. Wait, check carefully: The code is (8 + 2) * (5 - 3) ** 2 / 2 So (5-3)**2 = 2**2=4 Then 10 * 4 = 40 Then 40 / 2 = 20.0 So correct output is 20.0, option B.

❓ Predict Output

advanced

Output of negative number exponentiation

What does this code print?

Python

print(-3 ** 2)

A -9

B 9

C Error

D -6

💡 Hint

Exponentiation has higher priority than the unary minus.

The expression is interpreted as -(3 ** 2), so 3**2=9, then unary minus makes it -9.

🧠 Conceptual

expert

Understanding float division precision

What is the output of this code?

Python

result = 0.1 + 0.2
print(result == 0.3)

A None

B True

C False

D Error

💡 Hint

Floating point numbers can have small precision errors.

Due to how computers store floating point numbers, 0.1 + 0.2 is not exactly 0.3, so the comparison is False.

Practice

1. Which arithmetic operator in Python 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 % gives the remainder after division, // gives the floor division result, ** is for power, and + is for addition.

2. Step 2: Identify the operator for remainder

   The remainder operator is %, which returns the leftover part after dividing two numbers.

3. Final Answer:

   % -> Option C

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remainder operator looks like a percent sign % [OK]

Common Mistakes:

• Confusing // (floor division) with %
• Using ** instead of %
• Thinking + gives remainder

2. Which of the following is the correct operator syntax to calculate 5 to the power of 3 in Python?

easy

A. 5 ^ 3

B. pow(5, 3)

C. 5 ^^ 3

D. 5 ** 3

Solution

1. Step 1: Recall Python's power operator syntax

   Python uses ** to calculate powers, so 5 ** 3 means 5 to the power of 3.

2. Step 2: Check other options for correctness

   5 ^ 3 is bitwise XOR, 5 ^^ 3 is invalid syntax, and pow(5, 3) is a function call but not an operator syntax.

3. Final Answer:

   5 ** 3 -> Option D

4. Quick Check:

   Power operator = ** [OK]

Hint: Use ** for power, not ^ or ^^ [OK]

Common Mistakes:

• Using ^ instead of ** for power
• Trying ^^ which is invalid
• Confusing function pow() with operator syntax

3. What is the output of the following code?

result = 17 // 4
print(result)

medium

A. 4.25

B. 4

C. 1

D. Error

Solution

1. Step 1: Understand floor division operator //

   The operator // divides and returns the largest whole number less than or equal to the result.

2. Step 2: Calculate 17 // 4

   17 divided by 4 is 4.25, floor division drops the decimal part, so result is 4.

3. Final Answer:

   4 -> Option B

4. Quick Check:

   17 // 4 = 4 [OK]

Hint: Floor division drops decimals, so 17//4 is 4 [OK]

Common Mistakes:

• Confusing // with / which gives float
• Expecting 4.25 instead of 4
• Thinking // rounds up

4. Find the error in this code snippet:

num = 10
result = num % 0
print(result)

medium

A. ZeroDivisionError at runtime

B. No error, output is 0

C. SyntaxError due to % operator

D. TypeError because 0 is int

Solution

1. Step 1: Understand modulo operator with zero

   The modulo operator % cannot divide by zero; it causes an error.

2. Step 2: Identify the error type

   Dividing or modulo by zero raises a ZeroDivisionError at runtime.

3. Final Answer:

   ZeroDivisionError at runtime -> Option A

4. Quick Check:

   Modulo by zero causes ZeroDivisionError [OK]

Hint: Modulo by zero causes runtime error, never allowed [OK]

Common Mistakes:

• Thinking it causes syntax error
• Expecting output 0 instead of error
• Confusing with TypeError

5. You want to calculate the area of a square with side length stored in variable side. Which expression correctly uses arithmetic operators to do this?

hard

A. area = side ** 2

B. area = side // 2

C. area = side + side

D. area = side * 2

Solution

1. Step 1: Recall formula for square area

   The area of a square is side length multiplied by itself, or side squared.

2. Step 2: Match formula with operators

   Using side ** 2 calculates side to the power of 2, which is correct for area.

3. Final Answer:

   area = side ** 2 -> Option A

4. Quick Check:

   Square area = side squared = side ** 2 [OK]

Hint: Square area = side squared, use ** 2 [OK]

Common Mistakes:

• Using side * 2 which doubles side, not area
• Using side + side which adds sides, not area
• Using floor division // which is incorrect