Python Program to Check if a Number is Even or Odd

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Checking whether a number is even or odd is a basic yet essential task in programming. In Python, this can be done easily using a simple conditional check and the modulus operator (%). In this blog, we’ll walk you through how to write a Python program that checks if a number is even or odd, step by step.

What is an Even or Odd Number?

  • Even Number: A number that is divisible by 2 without leaving any remainder. For example, numbers like 2, 4, 6, and 10 are even.
  • Odd Number: A number that, when divided by 2, leaves a remainder of 1. Examples include 1, 3, 5, 7, and 9.

The main principle here is the modulus operation. If the remainder is 0 when the number is divided by 2, then the number is even. Otherwise, it’s odd.

Steps to Write the Program

  1. Input the Number: We’ll prompt the user to input a number.
  2. Use the Modulus Operator: The program will use the modulus operator (%) to check whether the number is divisible by 2.
  3. Conditional Statement: Based on the result of the modulus operation, we’ll determine if the number is even or odd.
  4. Display the Result: Finally, the program will print whether the number is even or odd.

Python Program to Check Even or Odd

# Python program to check if a number is even or odd

# Input: Asking the user to enter a number
number = int(input("Enter a number: "))

# Check if the number is even or odd using the modulus operator
if number % 2 == 0:
    print(f"{number} is an even number.")
else:
    print(f"{number} is an odd number.")

Explanation:

  1. Input: The input() function is used to take a number from the user. We use int() to ensure the input is converted to an integer.
  2. Modulo Operation: The expression number % 2 checks if the remainder when dividing the number by 2 is zero.
  • If the result is 0, the number is even.
  • If the result is anything other than 0, the number is odd.
  1. Output: Depending on the condition, the program prints either that the number is even or odd.

Sample Output

Test Case 1: Even Number

Enter a number: 8
8 is an even number.

Test Case 2: Odd Number

Enter a number: 7
7 is an odd number.

Test Case 3: Zero (Edge Case)

Enter a number: 0
0 is an even number.

Understanding the Modulo Operation

The modulo operator (%) is the key part of this program. The modulus operation returns the remainder when one number is divided by another. For instance:

  • 8 % 2 returns 0, because 8 is divisible by 2.
  • 7 % 2 returns 1, because 7 is not divisible by 2 (7 divided by 2 equals 3 with a remainder of 1).

The modulo operator is a common tool in programming for checking divisibility, especially in determining even and odd numbers.

Handling Edge Cases

  • Zero (0): In mathematics, zero is considered an even number. Our program correctly identifies this since 0 % 2 == 0.
  • Negative Numbers: The program will also work with negative numbers, identifying whether they are even or odd in the same way as positive numbers.

Example:

Enter a number: -4
-4 is an even number.

Enhancing the Program with Exception Handling

You can make your program more robust by handling invalid inputs (e.g., non-numeric values). This can be done using a try-except block:

# Python program to check if a number is even or odd with error handling

try:
    # Input: Asking the user to enter a number
    number = int(input("Enter a number: "))

    # Check if the number is even or odd using the modulus operator
    if number % 2 == 0:
        print(f"{number} is an even number.")
    else:
        print(f"{number} is an odd number.")

except ValueError:
    print("Invalid input! Please enter a valid integer.")

In this version, if the user enters something other than a number, the program will catch the ValueError and display a user-friendly message.

Conclusion

Checking if a number is even or odd is one of the most basic yet important concepts in programming. With Python, the task becomes very simple thanks to the modulus operator and the ease of conditional statements. Whether you’re working with positive, negative, or zero values, this program will help you quickly determine the classification of any number.

We also explored how you can enhance the program by adding exception handling, making it more user-friendly and resistant to errors.

Keep practicing, and soon you’ll be able to apply similar techniques to solve more complex problems. Happy coding!

By understanding this basic even-odd check, you’re laying a solid foundation in Python programming. Don’t stop here—keep building and refining your coding skills!

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