Arithmetic operators in Python

Introduction

Arithmetic operators help us do math with numbers in programs. They let us add, subtract, multiply, and divide easily.

Calculating the total price of items in a shopping cart.

Finding the difference in days between two dates.

Doubling a recipe ingredient amount.

Splitting a bill evenly among friends.

Converting temperatures between Celsius and Fahrenheit.

Syntax

Python

result = a + b  # addition
result = a - b  # subtraction
result = a * b  # multiplication
result = a / b  # division
result = a % b  # remainder (modulus)
result = a ** b # power (exponent)
result = a // b # floor division (whole number division)

Use + to add numbers.

Use - to subtract one number from another.

Examples

Adds 5 and 3, then prints 8.

Python

x = 5 + 3
print(x)

Subtracts 4 from 10, then prints 6.

Python

y = 10 - 4
print(y)

Multiplies 7 by 2, then prints 14.

Python

z = 7 * 2
print(z)

Divides 15 by 4, prints 3.75 (a float).

Python

a = 15 / 4
print(a)

Sample Program

This program shows all main arithmetic operations between 12 and 5 with clear labels.

Python

a = 12
b = 5
print(f"Addition: {a} + {b} = {a + b}")
print(f"Subtraction: {a} - {b} = {a - b}")
print(f"Multiplication: {a} * {b} = {a * b}")
print(f"Division: {a} / {b} = {a / b}")
print(f"Modulus: {a} % {b} = {a % b}")
print(f"Power: {a} ** {b} = {a ** b}")
print(f"Floor Division: {a} // {b} = {a // b}")

Important Notes

Division / always gives a float result, even if numbers divide evenly.

Floor division // gives the whole number part of division, dropping decimals.

Modulus % gives the remainder after division.

Summary

Arithmetic operators let you do basic math in code.

Use +, -, *, / for add, subtract, multiply, divide.

Other useful operators: % (remainder), ** (power), // (floor division).

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