Return values in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this function call?

Consider the following Python function. What will be printed when result = multiply_and_add(2, 3) is executed and then print(result) is called?

Python

def multiply_and_add(x, y):
    product = x * y
    sum_ = x + y
    return product + sum_

result = multiply_and_add(2, 3)
print(result)

A 11

B 10

C 5

D 6

💡 Hint

Remember to add both the product and the sum of the two numbers.

The function multiplies 2 and 3 to get 6, adds 2 and 3 to get 5, then returns their sum: 6 + 5 = 11.

❓ Predict Output

intermediate

What does this function return?

What is the output of the following code snippet?

Python

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

print(check_even(7))

A False

B True

C None

D 7

💡 Hint

Check if 7 is divisible by 2 without remainder.

7 is not divisible by 2 evenly, so the function returns False.

❓ Predict Output

advanced

What is the output of this recursive function?

What will be printed when the following code runs?

Python

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

print(factorial(4))

A 0

B 24

C 10

D 120

💡 Hint

Factorial of 4 is 4 * 3 * 2 * 1.

factorial(4) = 4 * factorial(3) = 4 * 3 * 2 * 1 = 24.

❓ Predict Output

advanced

What is the value of x after this function call?

What is the value of x after running the code below?

Python

def add_to_list(lst, item):
    lst.append(item)
    return lst

my_list = [1, 2]
x = add_to_list(my_list, 3)
print(x)

A None

B [1, 2]

C [3]

D [1, 2, 3]

💡 Hint

The function appends an item to the list and returns it.

The function adds 3 to the list [1, 2], so the returned list is [1, 2, 3].

❓ Predict Output

expert

What is the output of this function with multiple return statements?

What will be printed when the following code runs?

Python

def test_return(x):
    if x > 0:
        return 'Positive'
    elif x == 0:
        return 'Zero'
    return 'Negative'

print(test_return(-5))

A None

B Zero

C Negative

D Positive

💡 Hint

Check the conditions for x = -5.

Since -5 is less than 0, the function returns 'Negative'.

Practice

1. What does the return statement do in a Python function?

easy

A. It sends a value back to where the function was called.

B. It prints a value to the screen.

C. It creates a new variable inside the function.

D. It pauses the function without sending any value.

Solution

1. Step 1: Understand the purpose of return

   The return statement ends the function and sends a value back to the caller.

2. Step 2: Differentiate from printing or pausing

   Printing shows output but does not send a value back; pausing does not return a value.

3. Final Answer:

   It sends a value back to where the function was called. -> Option A

4. Quick Check:

   Return sends value back [OK]

Hint: Return sends value back, print shows output only [OK]

Common Mistakes:

• Confusing return with print
• Thinking return pauses without value
• Assuming return creates variables

2. Which of the following is the correct syntax to return the value 10 from a function?

easy

A. return(10,)

B. return 10

C. return = 10

D. return: 10

Solution

1. Step 1: Recall correct return syntax

   The correct syntax is simply return followed by the value without assignment or colon.

2. Step 2: Check each option

   return 10 is correct; return(10,) returns a tuple (10,) due to the trailing comma; the others cause syntax errors.

3. Final Answer:

   return 10 -> Option B

4. Quick Check:

   Return value with 'return value' syntax [OK]

Hint: Use 'return value' without assignment or colon [OK]

Common Mistakes:

• Using assignment with return
• Adding colon after return
• Using parentheses incorrectly

3. What is the output of this code?

def add(a, b):
    return a + b

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

medium

A. None

B. 34

C. 7

D. Error

Solution

1. Step 1: Understand the function behavior

   The function add returns the sum of a and b.

2. Step 2: Calculate the return value

   Calling add(3, 4) returns 7, which is stored in result and printed.

3. Final Answer:

   7 -> Option C

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Return value is sum, printed as 7 [OK]

Common Mistakes:

• Concatenating numbers as strings
• Forgetting to return value
• Expecting print inside function

4. Find the error in this function and choose the correct fix:

def multiply(x, y):
    product = x * y
    print(product)

medium

A. Add return x, y instead of product.

B. Change print(product) to return print(product).

C. Remove product and just print x * y.

D. Add return product to send the result back.

Solution

1. Step 1: Identify the problem

   The function prints the product but does not return it, so no value is sent back.

2. Step 2: Fix by returning the product

   Adding return product sends the result back to the caller.

3. Final Answer:

   Add return product to send the result back. -> Option D

4. Quick Check:

   Return value to send result back [OK]

Hint: Return value to send it back, print only shows output [OK]

Common Mistakes:

• Returning print() instead of value
• Not returning any value
• Returning wrong variables

5. You want a function that returns the first non-empty string from a list or None if all are empty. Which function correctly does this?

hard

A. def first_non_empty(strings):
for s in strings:
if s:
return s
return None

B. def first_non_empty(strings):
for s in strings:
if s == '':
return s
return None

C. def first_non_empty(strings):
for s in strings:
if not s:
return s
return None

D. def first_non_empty(strings):
for s in strings:
return s
return None

Solution

1. Step 1: Understand the goal

   The function should return the first string that is not empty (truthy) or None if none found.

2. Step 2: Analyze each option

   The version with if not s: return s returns the first falsy (empty) string; if s == '' returns the first exactly empty string; if s: return s returns the first truthy (non-empty) string; the version without if returns the first string regardless. Only the truthy check is correct.

3. Final Answer:

   def first_non_empty(strings): for s in strings: if s: return s return None -> Option A

4. Quick Check:

   Return first truthy string or None [OK]

Hint: Return first truthy value, else None [OK]

Common Mistakes:

• Returning empty strings instead of non-empty
• Returning on first loop without condition
• Confusing truthy and falsy values