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4.6.2 - Example 2: Check Even or Odd

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Understanding Conditions and the Modulo Operator

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Teacher
Teacher

Today, we're going to learn how to check whether a number is even or odd using a simple Python program. First, let's understand what the modulo operator does. Can anyone tell me what the modulo operator is?

Student 1
Student 1

Isn't the modulo operator used to find the remainder of a division?

Teacher
Teacher

Exactly, Student_1! For example, when we divide 5 by 2, the remainder is 1. So, we can use `%` to check if a number is even or odd. If `num % 2` equals 0, the number is even. Otherwise, it's odd. Can someone provide an example of what that looks like in Python?

Student 2
Student 2

Could you use 4 as an example? If we do `4 % 2`, it equals 0, so it's even!

Teacher
Teacher

Great illustration, Student_2! It’s a simple but powerful way to check conditions in programming.

Writing the Program

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Teacher
Teacher

Now, let’s write our program together. First, we need to get the user's input. What function do we use to take input in Python?

Student 3
Student 3

We can use the `input()` function!

Teacher
Teacher

That's correct, Student_3! Let's write the first line: `num = int(input('Enter a number: '))`. This will store the input as an integer in the variable `num`. What should we do next?

Student 4
Student 4

Now we need to add the `if` condition to check if this number is even or odd.

Teacher
Teacher

Right, Student_4! So we write: `if num % 2 == 0:` followed by the code to print 'Even'. In the `else` part, we'll print 'Odd'.

Student 1
Student 1

So the complete program prints whether the entered number is even or odd?

Teacher
Teacher

Exactly! Let’s summarize what we learned: We used input to capture a number, applied the modulo operator to check evenness, and created an `if-else` structure for decision-making.

Code Review and Testing

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Teacher
Teacher

Now that we’ve written our program, let’s test it out! What types of numbers should we test?

Student 3
Student 3

We should try both even and odd numbers to see if the program works correctly!

Teacher
Teacher

Good thinking! If we test with 8, what do you expect the output to be?

Student 2
Student 2

The output should say 'Even'!

Teacher
Teacher

Correct! And if we input 7, what should happen?

Student 4
Student 4

It should say 'Odd'!

Teacher
Teacher

Nice job! Testing different inputs helps us ensure our program functions as expected. Remember, always test extensively!

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section provides a practical example of a simple program in Python that checks if a number is even or odd.

Standard

The section illustrates how to use the modulo operator to determine whether an input number is even or odd through a straightforward Python program, emphasizing the use of conditional statements for decision-making in programming.

Detailed

Detailed Summary

In this section, we explore an example of a simple program written in Python that checks whether a given number is even or odd. The program utilizes the modulo operator (%), which gives the remainder of a division. When a number is divided by 2, if the remainder is 0, the number is classified as even; otherwise, it's odd.

Key Concepts:

  • Input Handling: The program begins by requesting input from the user.
  • Conditional Statements: It uses an if-else construct to make decisions based on the remainder of the number when divided by 2.
  • Output Display: Finally, it provides output to the user indicating whether the given number is even or odd.

This practical example helps reinforce fundamental programming concepts such as variables, control structures, and input/output operations.

Audio Book

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Input a Number

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Code Editor - python

Detailed Explanation

In this chunk, we are asking the user to enter a number. The input() function captures the user's input as a string, and the int() function converts that string into an integer so that we can perform numerical operations on it.

Examples & Analogies

Think of this step as asking someone their age. When they tell you '15', you need to convert that spoken word into a number (15) to understand how old they actually are.

Checking Even or Odd

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Detailed Explanation

This chunk contains a conditional statement that checks if the number is even or odd. The % operator calculates the remainder when num is divided by 2. If the remainder is 0, the number is even, and 'Even' is printed. If the remainder is not 0, the number is odd, and 'Odd' is printed instead.

Examples & Analogies

Imagine you have a group of friends, and you want to pair them up for a game. If you have an even number of friends, everyone gets a partner, which is like the number being 'Even'. But if one friend is left out, they don't have a partner, which represents the number being 'Odd'.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Input Handling: The program begins by requesting input from the user.

  • Conditional Statements: It uses an if-else construct to make decisions based on the remainder of the number when divided by 2.

  • Output Display: Finally, it provides output to the user indicating whether the given number is even or odd.

  • This practical example helps reinforce fundamental programming concepts such as variables, control structures, and input/output operations.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • Using the program, if the input is 4, the output will be 'Even'.

  • If the input is 7, the output will be 'Odd'.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • To find if a number's neat (even) or odd, divide by two with a nod!

📖 Fascinating Stories

  • Once there was a number named 'Seven'. It wanted to know if it was cool. So, it went to a wise old teacher named Python, who said, 'If you divide me by 2 and the remainder's not seen, you’re even like a queen!'

🧠 Other Memory Gems

  • E.O. (Even - Odd) can help you remember: Even means 0 remainder, Odd means 1 remainder.

🎯 Super Acronyms

EOP (Even or Odd Program)

  • E: for Even
  • O: for Odd
  • P: for Program helps us recall how to check.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Even Number

    Definition:

    An integer that is divisible by 2 with no remainder.

  • Term: Odd Number

    Definition:

    An integer that is not divisible by 2 without a remainder.

  • Term: Modulo Operator

    Definition:

    A mathematical operator that returns the remainder of a division operation.

  • Term: Conditional Statement

    Definition:

    A programming construct that allows execution of certain code based on whether a condition evaluates to true or false.

  • Term: Input

    Definition:

    Data that is received by a program from the user.

  • Term: Output

    Definition:

    The data that is sent from a program to the user.

while True

num = int(input('Enter a number (0 to stop): '))

if num == -1

break

if num % 2 == 0 print('Even')

else: print('Odd')

  • Hint: Think about how to implement a stopping condition.
  • Problem: Modify the program to count how many even and how many odd numbers have been inputted by the user.
  • Solution: // Pseudocode Example:
    // even_count = 0
    // odd_count = 0
    // while True:
    // num = int(input('Enter a number (or -1 to exit): '))
    // if num == -1:
    // break
    // if num % 2 == 0:
    // even_count += 1
    // else:
    // odd_count += 1
    // print('Even count:', even_count, 'Odd count:', odd_count)
  • Hint: Consider how to maintain and update counters for even and odd inputs.

if num == 0

break