4.6.2 - Example 2: Check Even or Odd
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Interactive Audio Lesson
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Understanding Conditions and the Modulo Operator
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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?
Isn't the modulo operator used to find the remainder of a division?
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?
Could you use 4 as an example? If we do `4 % 2`, it equals 0, so it's even!
Great illustration, Student_2! It’s a simple but powerful way to check conditions in programming.
Writing the Program
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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?
We can use the `input()` function!
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?
Now we need to add the `if` condition to check if this number is even or odd.
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'.
So the complete program prints whether the entered number is even or odd?
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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Now that we’ve written our program, let’s test it out! What types of numbers should we test?
We should try both even and odd numbers to see if the program works correctly!
Good thinking! If we test with 8, what do you expect the output to be?
The output should say 'Even'!
Correct! And if we input 7, what should happen?
It should say 'Odd'!
Nice job! Testing different inputs helps us ensure our program functions as expected. Remember, always test extensively!
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
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-elseconstruct 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
Chapter 1 of 2
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Chapter Content
num = int(input("Enter a number: "))
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
Chapter 2 of 2
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Chapter Content
if num % 2 == 0:
print("Even")
else:
print("Odd")
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'.
Key Concepts
-
Input Handling: The program begins by requesting input from the user.
-
Conditional Statements: It uses an
if-elseconstruct 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 & Applications
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
Interactive tools to help you remember key concepts
Rhymes
To find if a number's neat (even) or odd, divide by two with a nod!
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!'
Memory Tools
E.O. (Even - Odd) can help you remember: Even means 0 remainder, Odd means 1 remainder.
Acronyms
EOP (Even or Odd Program)
for Even
for Odd
for Program helps us recall how to check.
Flash Cards
Glossary
- Even Number
An integer that is divisible by 2 with no remainder.
- Odd Number
An integer that is not divisible by 2 without a remainder.
- Modulo Operator
A mathematical operator that returns the remainder of a division operation.
- Conditional Statement
A programming construct that allows execution of certain code based on whether a condition evaluates to true or false.
- Input
Data that is received by a program from the user.
- Output
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
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