This content originally appeared on DEV Community and was authored by Sabin Sim
Day 3 – Operators
Project: Build a “Smart Grade Calculator”
01. Learning Goal
By the end of this lesson, you will be able to:
- Use Python’s arithmetic, comparison, and logical operators
- Understand operator precedence
- Combine operators to create expressions
- Build a small project that evaluates pass/fail and excellence
02. Problem Scenario
You are designing a simple “Smart Grade Calculator”.
The program will calculate total points, compare grades, and determine if a student passes or is excellent using logical operators.
03. Step 1 – Arithmetic Operators
Used for basic mathematical operations.
| Operator | Meaning | Example | Result |
|---|---|---|---|
+ |
Addition | 5 + 2 |
7 |
- |
Subtraction | 5 - 2 |
3 |
* |
Multiplication | 5 * 2 |
10 |
/ |
Division (float) | 5 / 2 |
2.5 |
// |
Floor Division | 5 // 2 |
2 |
% |
Modulus (Remainder) | 5 % 2 |
1 |
** |
Exponentiation | 2 ** 3 |
8 |
Example:
a = 7
b = 3
print(a + b) # 10
print(a / b) # 2.333...
print(a // b) # 2
print(a % b) # 1
print(a ** b) # 343
04. Step 2 – Comparison Operators
Used to compare values. The result is always True or False.
| Operator | Meaning | Example | Result |
|---|---|---|---|
== |
Equal to | 5 == 5 |
True |
!= |
Not equal to | 5 != 3 |
True |
> |
Greater than | 5 > 3 |
True |
< |
Less than | 5 < 3 |
False |
>= |
Greater or equal | 5 >= 5 |
True |
<= |
Less or equal | 3 <= 5 |
True |
Example:
x = 10
y = 20
print(x == y) # False
print(x != y) # True
print(x < y) # True
05. Step 3 – Logical Operators
Used to combine multiple conditions.
| Operator | Meaning | Example | Result |
|---|---|---|---|
and |
Both must be True | True and False |
False |
or |
Either can be True | True or False |
True |
not |
Negation | not True |
False |
Example:
age = 25
is_student = False
print(age > 18 and is_student) # False (one is False)
print(age > 18 or is_student) # True (one is True)
print(not is_student) # True (negation)
06. Step 4 – Operator Precedence
Operations are executed in the following order:
Multiplication / Division → Addition / Subtraction
Use parentheses ( ) to control order.
print(2 + 3 * 4) # 14 (multiplication first)
print((2 + 3) * 4) # 20 (parentheses first)
07. Step 5 – Practice Examples
Example 1: Arithmetic Practice
x = 15
y = 4
print("Quotient:", x // y)
print("Remainder:", x % y)
print("Power:", x ** y)
Example 2: Comparison Practice
temperature = 30
print("Is it hot?", temperature > 25)
print("Is it cold?", temperature < 10)
Example 3: Logical Practice
score = 85
is_pass = score >= 60
is_excellent = score >= 90
print("Passed?", is_pass)
print("Excellent?", is_excellent)
print("Pass & Excellent?", is_pass and is_excellent)
08. Step 6 – Mini Project: Smart Grade Calculator
Build a program that evaluates a student’s performance.
name = "Sabin"
score = 88
print(f"Student: {name}")
print("Passed?", score >= 60)
print("Excellent?", score >= 90)
print("Pass but not Excellent?", score >= 60 and score < 90)
09. Reflection
You have learned how to:
- Perform mathematical operations
- Compare and combine logical conditions
- Understand operator precedence
- Build a simple Smart Grade Calculator
This knowledge is essential for decision-making logic you’ll use in conditionals, loops, and full applications later.
This content originally appeared on DEV Community and was authored by Sabin Sim