Assignment and augmented assignment in Python - Mini Project: Build & Apply

Assignment and Augmented Assignment

📖 Scenario: You are managing a small shop's daily sales. You want to keep track of the total sales amount as you add new sales throughout the day.

🎯 Goal: Build a simple program that starts with an initial sales amount, then adds more sales using assignment and augmented assignment operators, and finally shows the total sales.

📋 What You'll Learn

Create a variable to hold the initial sales amount.

Create a variable to hold the new sales amount.

Use an assignment operator to set the initial total sales.

Use an augmented assignment operator to add new sales to the total.

Print the final total sales amount.

💡 Why This Matters

🌍 Real World

Tracking sales or any running total is common in shops, restaurants, and many businesses.

💼 Career

Understanding assignment and augmented assignment is essential for managing data and calculations in programming jobs.

1

Create initial sales variables

Create a variable called initial_sales and set it to 150. Then create a variable called new_sales and set it to 75.

Python

# Create variables initial_sales and new_sales with values 150 and 75
# Your code here

Hint

Use simple assignment with = to set the values.

2

Set total sales with assignment

Create a variable called total_sales and assign it the value of initial_sales using the assignment operator =.

Python

initial_sales = 150
new_sales = 75
# Assign total_sales to initial_sales
# Your code here

Hint

Use = to copy the value from initial_sales to total_sales.

3

Add new sales using augmented assignment

Use the augmented assignment operator += to add new_sales to total_sales.

Python

initial_sales = 150
new_sales = 75
total_sales = initial_sales
# Add new_sales to total_sales using +=
# Your code here

Hint

The += operator adds the right side value to the left side variable.

4

Print the total sales

Write a print statement to display the value of total_sales.

Python

initial_sales = 150
new_sales = 75
total_sales = initial_sales
total_sales += new_sales
# Print total_sales
# Your code here

Hint

Use print(total_sales) to show the final total.

Practice

1.

What does the += operator do in Python?

easy

A. Adds the right value to the left variable and updates it

B. Assigns a new variable without changing the old one

C. Subtracts the right value from the left variable

D. Creates a new list from two variables

Solution

1. Step 1: Understand the meaning of +=

   The += operator adds the value on the right to the variable on the left.

2. Step 2: Recognize it updates the variable

   It changes the original variable by adding the new value to it.

3. Final Answer:

   Adds the right value to the left variable and updates it -> Option A

4. Quick Check:

   += means add and assign [OK]

Hint: Think: add then store back in same variable [OK]

Common Mistakes:

• Confusing += with simple assignment =
• Thinking += creates a new variable
• Mixing += with subtraction or multiplication

2.

Which of the following is the correct syntax to add 5 to variable x using augmented assignment?

x = 10
# Add 5 to x here

easy

A. x =+ 5

B. x += 5

C. x =+5

D. x = x +

Solution

1. Step 1: Identify correct augmented assignment syntax

   The correct syntax to add and assign is x += 5.

2. Step 2: Check other options for syntax errors

   Choices like x =+ 5 and x =+5 use incorrect operator placement; x = x + is incomplete.

3. Final Answer:

   x += 5 -> Option B

4. Quick Check:

   Use += for adding and assigning [OK]

Hint: Remember: operator before equals for augmented assignment [OK]

Common Mistakes:

• Writing =+ instead of +=
• Leaving out the value after +
• Using incomplete expressions

3.

What is the output of this code?

count = 3
count += 4
count -= 2
print(count)

medium

A. 9

B. 7

C. 3

D. 5

Solution

1. Step 1: Calculate count += 4

   Starting from 3, adding 4 gives 7.

2. Step 2: Calculate count -= 2

   Subtracting 2 from 7 gives 5.

3. Final Answer:

   5 -> Option D

4. Quick Check:

   3 + 4 - 2 = 5 [OK]

Hint: Follow each operation step-by-step [OK]

Common Mistakes:

• Adding and subtracting in wrong order
• Confusing += and -= effects
• Ignoring the initial value

4.

Find the error in this code snippet:

total = 10
total + = 5
print(total)

medium

A. TypeError because + cannot be used with int

B. NameError because total is not defined

C. SyntaxError due to space in augmented assignment

D. No error, prints 15

Solution

1. Step 1: Check augmented assignment syntax

   The operator += must not have spaces between + and =.

2. Step 2: Identify the error caused by space

   Writing + = causes a SyntaxError in Python.

3. Final Answer:

   SyntaxError due to space in augmented assignment -> Option C

4. Quick Check:

   No spaces allowed in += operator [OK]

Hint: No spaces between + and = in augmented assignment [OK]

Common Mistakes:

• Adding spaces inside augmented assignment operator
• Assuming it works like normal addition
• Ignoring syntax error messages

5.

You have a variable score = 50. You want to increase it by 10%, then subtract 5 using augmented assignments. Which code correctly does this?

score = 50
# Increase by 10%
# Subtract 5

hard

A. score *= 1.1
score -= 5

B. score += 10
score -= 5

C. score = score + 10%
score = score - 5

D. score += 0.1
score -= 5

Solution

1. Step 1: Increase score by 10%

   Multiplying by 1.1 increases the value by 10%, so score *= 1.1 is correct.

2. Step 2: Subtract 5 using augmented assignment

   Use score -= 5 to subtract 5 from the updated score.

3. Final Answer:

   score *= 1.1 score -= 5 -> Option A

4. Quick Check:

   Multiply by 1.1 then subtract 5 [OK]

Hint: Use *= for percent increase, then -= for subtraction [OK]

Common Mistakes:

• Adding 10 instead of 10%
• Using invalid syntax like 10%
• Not updating score before subtracting