Why variables are needed in Python - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to store the number 10 in a variable named 'age'.

Python

age = [1]

Drag options to blanks, or click blank then click option'

Aage

B'age'

C10

Dten

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around 10 makes it a string, not a number.

The variable age stores the number 10 so we can use it later in the program.

2fill in blank

medium

Complete the code to print the value stored in the variable 'name'.

Python

print([1])

Drag options to blanks, or click blank then click option'

AName

Bname

Cprint

D'name'

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes prints the variable name as text, not its value.

To print the value inside the variable name, just write its name without quotes.

3fill in blank

hard

Fix the error in the code by completing the assignment of 5 to the variable 'count'.

Python

count [1] 5

Drag options to blanks, or click blank then click option'

A=

B==

C===

D:=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '=' causes a syntax error here.

The single equals sign = assigns the value 5 to the variable count.

4fill in blank

hard

Fill both blanks to create a variable 'total' that adds 3 and 7.

Python

total = [1] [2] 7

Drag options to blanks, or click blank then click option'

A3

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus or multiplication changes the result.

The variable total stores the sum of 3 and 7 using the plus sign +.

5fill in blank

hard

Fill all three blanks to create a variable 'message' that stores 'Hello' repeated 3 times.

Python

message = [1] [2] [3]

Drag options to blanks, or click blank then click option'

A'Hello'

B*

C3

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using plus + concatenates strings, not repeats them.

The variable message stores the string 'Hello' repeated 3 times using the * operator.

Practice

1. Why do we use variables in a Python program?

easy

A. To create new Python functions

B. To make the program run faster

C. To print text on the screen

D. To store information that can be used later

Solution

1. Step 1: Understand the role of variables

   Variables hold data so the program can use or change it later.

2. Step 2: Compare options with variable purpose

   Only storing information matches what variables do; others are unrelated.

3. Final Answer:

   To store information that can be used later -> Option D

4. Quick Check:

   Variables store data for later use [OK]

Hint: Variables hold data for reuse later in code [OK]

Common Mistakes:

• Thinking variables speed up the program
• Confusing variables with functions
• Believing variables print output directly

2. Which of the following is the correct way to create a variable named age with the value 25 in Python?

easy

A. int age = 25

B. age = 25

C. age := 25

D. 25 = age

Solution

1. Step 1: Recall Python variable assignment syntax

   Python uses variable = value to assign values.

2. Step 2: Check each option

   age = 25 matches correct syntax; B reverses assignment; C uses walrus operator incorrectly here; A is Java style.

3. Final Answer:

   age = 25 -> Option B

4. Quick Check:

   Variable assignment uses = sign correctly [OK]

Hint: Use variable = value to assign in Python [OK]

Common Mistakes:

• Putting value before variable
• Using := instead of = for simple assignment
• Using Java or other language syntax

3. What will be the output of this code?

name = "Anna"
print("Hello, " + name)

medium

A. Hello, Anna

B. Hello, name

C. Hello,

D. Error

Solution

1. Step 1: Understand variable value and string concatenation

   The variable name holds "Anna". The print joins "Hello, " and the value of name.

2. Step 2: Predict the printed result

   Concatenation results in "Hello, Anna" being printed.

3. Final Answer:

   Hello, Anna -> Option A

4. Quick Check:

   Concatenate string + variable value = Hello, Anna [OK]

Hint: Variables replace names with stored values in output [OK]

Common Mistakes:

• Printing variable name as text instead of value
• Forgetting to concatenate strings
• Expecting an error from string + variable

4. Find the error in this code:

number = 10
print(numer)

medium

A. Missing quotes around number

B. Assignment operator is wrong

C. Variable name typo causes error

D. Print statement syntax error

Solution

1. Step 1: Compare variable names used

   The variable is named number, but print uses numer, which is undefined.

2. Step 2: Identify error type

   This typo causes a NameError because numer does not exist.

3. Final Answer:

   Variable name typo causes error -> Option C

4. Quick Check:

   Variable names must match exactly [OK]

Hint: Check variable spelling carefully to avoid NameError [OK]

Common Mistakes:

• Assuming print needs quotes for variables
• Thinking assignment operator is wrong
• Believing print syntax is incorrect

5. You want to calculate the total price of 3 items costing 10, 15, and 20 dollars. Which code correctly uses variables to do this?

hard

A. price1 = 10
price2 = 15
price3 = 20
total = price1 + price2 + price3
print(total)

B. print(10 + 15 + 20)

C. total = price1 + price2 + price3
price1 = 10
price2 = 15
price3 = 20
print(total)

D. total = 10 + 15 + 20
print(total)

Solution

1. Step 1: Check variable assignments before use

   Variables price1, price2, and price3 must be assigned values before adding.

2. Step 2: Analyze each option

   price1 = 10 price2 = 15 price3 = 20 total = price1 + price2 + price3 print(total) assigns prices first, then sums them. total = 10 + 15 + 20 print(total) sums constants directly (no variables for prices). print(10 + 15 + 20) prints sum directly without variables. total = price1 + price2 + price3 price1 = 10 price2 = 15 price3 = 20 print(total) sums variables before assigning them, causing error.

3. Final Answer:

   price1 = 10 price2 = 15 price3 = 20 total = price1 + price2 + price3 print(total) -> Option A

4. Quick Check:

   Assign variables before use, then sum [OK]

Hint: Assign variables before using them in calculations [OK]

Common Mistakes:

• Using variables before assigning values
• Adding numbers directly without variables
• Confusing order of assignment and calculation