Methods with parameters in Python - Mini Project: Build & Apply

Methods with parameters

📖 Scenario: You are creating a simple calculator program that can add two numbers. This program will help users quickly add any two numbers they want.

🎯 Goal: Build a program with a method that takes two numbers as parameters and returns their sum. Then, use this method to add two specific numbers and show the result.

📋 What You'll Learn

Create a method that accepts two parameters

Return the sum of the two parameters

Call the method with two numbers

Print the result of the method call

💡 Why This Matters

🌍 Real World

Methods with parameters are used in almost every program to perform tasks with different inputs, like calculators, games, or data processing.

💼 Career

Understanding how to write and use methods with parameters is a key skill for software developers to create reusable and organized code.

1

Create the method with parameters

Write a method called add_numbers that takes two parameters named num1 and num2. Inside the method, return the sum of num1 and num2.

Python

# Define the method add_numbers with parameters num1 and num2
# Your code here

Hint

Remember to use def to create a method and include both parameters inside the parentheses.

2

Set two numbers to add

Create two variables called first_number and second_number. Set first_number to 8 and second_number to 12.

Python

def add_numbers(num1, num2):
    return num1 + num2

# Create variables first_number and second_number with values 8 and 12
# Your code here

Hint

Use simple assignment to set the variables to the exact numbers.

3

Call the method with the numbers

Create a variable called result and set it to the value returned by calling add_numbers with first_number and second_number as arguments.

Python

def add_numbers(num1, num2):
    return num1 + num2

first_number = 8
second_number = 12

# Call add_numbers with first_number and second_number and store in result
# Your code here

Hint

Call the method by passing the two variables inside the parentheses.

4

Print the result

Write a print statement to display the value of the variable result.

Python

def add_numbers(num1, num2):
    return num1 + num2

first_number = 8
second_number = 12

result = add_numbers(first_number, second_number)

# Print the result
# Your code here

Hint

Use print(result) to show the sum on the screen.

Practice

1. What is the purpose of parameters in a Python method?

easy

A. To accept inputs that the method can use

B. To store data permanently

C. To print output automatically

D. To create new variables outside the method

Solution

1. Step 1: Understand what parameters do

   Parameters allow a method to receive inputs when it is called.

2. Step 2: Identify the correct purpose

   Parameters are not for storing data permanently or printing output; they are for input.

3. Final Answer:

   To accept inputs that the method can use -> Option A

4. Quick Check:

   Parameters = inputs [OK]

Hint: Parameters let methods take inputs to work with [OK]

Common Mistakes:

• Thinking parameters store data permanently
• Confusing parameters with output
• Believing parameters create variables outside method

2. Which of the following is the correct way to define a method with two parameters a and b in Python?

easy

A. def my_method{a, b}:

B. def my_method[a, b]:

C. def my_method(a, b):

D. def my_method a, b:

Solution

1. Step 1: Recall Python method syntax

   Methods use parentheses () to list parameters separated by commas.

2. Step 2: Identify correct syntax

   Only def my_method(a, b): uses parentheses and commas correctly.

3. Final Answer:

   def my_method(a, b): -> Option C

4. Quick Check:

   Method parameters use ( ) and commas [OK]

Hint: Use parentheses and commas to list parameters [OK]

Common Mistakes:

• Using square brackets instead of parentheses
• Using curly braces instead of parentheses
• Omitting parentheses around parameters

3. What will be the output of the following code?

def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))

medium

A. Hello, name!

B. Error: name not defined

C. greet(Alice)

D. Hello, Alice!

Solution

1. Step 1: Understand the method call

   The method greet is called with argument "Alice" passed to parameter name.

2. Step 2: Evaluate the return statement

   The method returns the string "Hello, Alice!" using f-string formatting.

3. Final Answer:

   Hello, Alice! -> Option D

4. Quick Check:

   Method returns greeting with input name [OK]

Hint: Arguments replace parameters when method runs [OK]

Common Mistakes:

• Printing the parameter name instead of its value
• Confusing method name with output
• Expecting an error due to missing quotes

4. Find the error in this method definition:

def add_numbers(x, y)
    return x + y

medium

A. Parameters should be inside square brackets

B. Missing colon after parameter list

C. Return statement should be outside the method

D. Parameters must be strings

Solution

1. Step 1: Check method syntax

   Python method definitions require a colon ':' after the parameter list.

2. Step 2: Identify missing colon

   The code misses the colon after (x, y), causing syntax error.

3. Final Answer:

   Missing colon after parameter list -> Option B

4. Quick Check:

   Method header ends with ':' [OK]

Hint: Always put ':' after method parameters [OK]

Common Mistakes:

• Forgetting colon after parameters
• Using wrong brackets for parameters
• Misplacing return statement

5. You want to create a method calculate_area that takes two parameters width and height and returns their product. Which code correctly implements this?

hard

A. def calculate_area(width, height):
return width * height

B. def calculate_area(width, height):
return width + height

C. def calculate_area(width, height):
print(width * height)

D. def calculate_area(width, height):
return width / height

Solution

1. Step 1: Understand the method goal

   The method should return the product (multiplication) of width and height.

2. Step 2: Check each option's return value

   def calculate_area(width, height): return width * height returns width * height, which is correct. Others return sum, print output, or division.

3. Final Answer:

   def calculate_area(width, height):\n return width * height -> Option A

4. Quick Check:

   Area = width x height [OK]

Hint: Use * operator to multiply parameters for area [OK]

Common Mistakes:

• Using + instead of * for multiplication
• Printing instead of returning value
• Dividing instead of multiplying