L5 Operators

When you use a calculator, you press buttons for addition, subtraction, or multiplication. In Python, operators perform these calculations in code. Operators allow us to manipulate data, compare values, and make logical decisions.

💡 Analogy: Operators are like traffic signs—they tell Python what action to take when processing data.

Learning Objectives

1. Understand and use arithmetic operators in Python.

2. Use comparison operators to compare values.

3. Apply logical operators to make decisions in programs.

Key Terms

• Arithmetic operators – Symbols used to perform mathematical calculations (+, -, *, /, %).

• Comparison operators – Symbols used to compare values (==, !=, >, <, >=, <=) and return True or False.

• Logical operators – Operators (and, or, not) used to combine multiple conditions in decision-making.

• Order of operations – The rules that define which mathematical operations are performed first (e.g., multiplication before addition).

• Modulus operator (%) – Returns the remainder of a division operation (10 % 3 returns 1). In 10 % 3, we divide 10 by 3. 3 fits three times into 10 (3 × 3 = 9), and 1 is left over. The modulus operator gives us this leftover number. So, 10 % 3 gives 1 because 10 divided by 3 leaves a remainder of 1. This is a nice and simple technique for testing if a number is even or odd. 

Examples

x = 10

y = 5

print(x + y)  # Addition: 15

print(x > y)  # Comparison: True

print(x > 5 and y < 10)  # Logical: True

print(10 % 3)  # Modulus: Returns 1

🛑 Common Mistakes

1. Using = instead of == for comparison: if x = 5: ❌ is incorrect, use if x == 5: ✅.

2. Forgetting parentheses in complex operations: 10 + 5 * 2 evaluates as 10 + (5 * 2), not (10 + 5) * 2.