Python Functions Exercises

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You are learning about functions in Python and want to understand how they help organize and reuse code. A function in Python is defined using the `def` keyword and can be reused by calling it with parentheses.

Which of the following code snippets correctly defines and calls a function in Python?

function greet()
    print("Hello, Python!")
end

def greet:
    print("Hello, Python!")
greet()

def greet():
    print("Hello, Python!")
greet()

define greet():
    print("Hello, Python!")
greet()

Python uses the def keyword to define a function, followed by the function name and parentheses ().

The correct syntax looks like this:

def greet():
    print("Hello, Python!")
greet()

A colon : is required after the function definition line.
The function body must be properly indented.
The function is called using its name followed by parentheses.

Options 1, 2, and 4 use incorrect syntax or invalid keywords (like function, define, or missing colons).
Option 3 is the correct Python way to define and call a function.

What will be the output of the following code?

def greet():
    print("Hello")

greet()

Hello

greet()

None

Error

When greet() is called, the function executes and prints "Hello" to the output.

Which of the following is the correct way to pass a parameter to a function?

def add(a, b):
    return a + b

add(a b)

add(2, 3)

add(2 3)

add = (2, 3)

Function parameters should be passed inside parentheses, separated by commas. add(2, 3) correctly passes 2 and 3 to the function.

What will be the output of the following code?

def multiply(x, y):
    return x * y

result = multiply(3, 4)
print(result)

Error

The function multiply takes two parameters and returns their product. Calling multiply(3, 4) returns 12, which is printed.

What does this function return?

def check_even(num):
    if num % 2 == 0:
        return True
    else:
        return False

Returns the square of the number

Checks whether the number is prime

Checks if the number is even and returns True or False

Always returns False

The function uses the modulus operator to check if a number is divisible by 2. If so, it returns True, meaning the number is even. Otherwise, it returns False.

What will be printed by this code?

def show():
    return "Hi"

print(show())

None

show()

Error

The function show() returns the string "Hi", and the print statement outputs this string. So "Hi" is printed.

What will be the result of this function call?

def repeat(word, times):
    return word * times

print(repeat("Hi", 3))

HiHiHi

Hi 3

Hi Hi Hi

Error

Strings can be multiplied by integers in Python to repeat them. "Hi" * 3 results in "HiHiHi".

What will be the output of this recursive function?

def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n - 1)

print(factorial(4))

This is a recursive implementation of factorial. The call factorial(4) returns 4 * 3 * 2 * 1 = 24. Base case is when n == 0, it returns 1.

Which of these function calls will result in an error if the function is defined as:

def greet(name, msg="Hello"):
    print(msg, name)

greet("Alice")

greet("Alice", "Hi")

greet()

greet(name="Bob")

The parameter name is required. If you call greet() with no arguments, it throws a TypeError because Python expects at least one positional argument for name.

What is the output of the following code snippet?

def add_items(item, items=[]):
    items.append(item)
    return items

print(add_items("apple"))
print(add_items("banana"))

['apple']
['banana']

['apple', 'banana']
['banana']

['apple']
['apple', 'banana']

Default mutable arguments like lists are only evaluated once when the function is defined. So items persists across calls, leading to the second call appending to the same list.

What will the following function return?

def mystery(a, b):
    return a if a > b else b

print(mystery(4, 7))

True

None

The function uses a conditional expression to return the greater of a and b. Since 7 is greater than 4, it returns 7.

What will be the output of the following code?

def outer():
    x = "local"
    def inner():
        nonlocal x
        x = "nonlocal"
    inner()
    return x

print(outer())

local

nonlocal

global

Error

The nonlocal keyword allows the inner function to modify the variable x in the enclosing scope. So, x is updated to "nonlocal", and the function returns that value.

Which of the following will NOT cause an error?

def sample(a, b, /, c, d):
    print(a, b, c, d)

sample(1, 2, 3, 4)

sample(1, 2, c=3, d=4)

sample(1, b=2, c=3, d=4)

The syntax / indicates that the parameters before it (a, b) must be positional-only. Option 3 satisfies that rule. Option 2 and 4 incorrectly use keyword arguments for positional-only parameters.

What does this function return?

def func(a, b=[]):
    b.append(a)
    return b

print(func(1))
print(func(2))

[1] and [2]

[1] and [1, 2]

[1, 2] and [2]

Error

Default mutable arguments are shared between function calls. The list b retains its state from the previous call, resulting in [1] and then [1, 2].

What will this code print?

def func(x):
    return lambda y: x + y

add_5 = func(5)
print(add_5(3))

Error

Function object

The function func returns a lambda that adds x and y. When add_5 is called with 3, it returns 5 + 3 = 8.

About This Exercise: Python – Functions

Welcome to the Python Functions exercises — a dedicated set of challenges focused on helping you master one of the most powerful building blocks in Python programming: functions. Whether you're a beginner learning how to define and call your first function, or you're revisiting functions to strengthen your grasp on scopes, parameters, and return values, this section is for you.

Functions in Python are used to break down code into reusable blocks, making programs more organized, readable, and maintainable. These exercises will take you from the basics of defining and calling simple functions to more advanced topics like default arguments, keyword arguments, variable-length arguments (*args and **kwargs), lambda expressions, and recursion.

You'll also explore the concept of local and global scope, understand the lifetime of variables, and learn how to return values effectively for clean and modular code. These are essential concepts for writing scalable Python applications, whether you're working on automation scripts, web backends, or data processing tasks.

Each problem is designed with real-world programming in mind, allowing you to solve practical challenges that mirror those faced in actual software projects. As you progress, you’ll build the habit of thinking in terms of smaller, testable units — a crucial mindset in writing robust and maintainable code.

The Python Functions section is also a great opportunity to prepare for technical interviews, where questions around recursion, nested functions, and parameter behaviors are very common. Our structured set of exercises gradually increases in complexity to ensure you build confidence and skill at a comfortable pace.

In addition to solving these problems, we recommend exploring related topics like Python modules, decorators, and lambda functions, which build directly upon the core concept of functions. Also, don’t miss out on our quizzes to reinforce your learning and assess your understanding of how functions work in different scenarios.

Start practicing now and develop the ability to think modularly and write cleaner, more efficient code using Python functions. This foundational skill will pay off in every Python project you work on — from data science to web development to automation.

Python Functions Exercises

You are learning about functions in Python and want to understand how they help organize and reuse code. A function in Python is defined using the `def` keyword and can be reused by calling it with parentheses.

Which of the following code snippets correctly defines and calls a function in Python?

What will be the output of the following code?

What does the return statement do in a function?

How do you call a function named calculate in Python?

Which of the following is the correct way to pass a parameter to a function?

What will be the output of the following code?

What does this function return?

What will be printed by this code?

Which of the following is a valid function with default parameter values?

What will be the result of this function call?

What will be the output of this recursive function?

Which of these function calls will result in an error if the function is defined as:

What is the output of the following code snippet?

What will the following function return?

What is the purpose of the *args parameter in a function?

What will be the output of the following code?

Which of the following will NOT cause an error?

What does this function return?

What will this code print?

Which statement about Python function parameters is TRUE?

About This Exercise: Python – Functions

Python Functions Exercises

You are learning about functions in Python and want to understand how they help organize and reuse code. A function in Python is defined using the def keyword and can be reused by calling it with parentheses.

Which of the following code snippets correctly defines and calls a function in Python?

What will be the output of the following code?

What does the return statement do in a function?

How do you call a function named calculate in Python?

Which of the following is the correct way to pass a parameter to a function?

What will be the output of the following code?

What does this function return?

What will be printed by this code?

Which of the following is a valid function with default parameter values?

What will be the result of this function call?

What will be the output of this recursive function?

Which of these function calls will result in an error if the function is defined as:

What is the output of the following code snippet?

What will the following function return?

What is the purpose of the *args parameter in a function?

What will be the output of the following code?

Which of the following will NOT cause an error?

What does this function return?

What will this code print?

Which statement about Python function parameters is TRUE?

About This Exercise: Python – Functions

You are learning about functions in Python and want to understand how they help organize and reuse code. A function in Python is defined using the `def` keyword and can be reused by calling it with parentheses.