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Sabin Sim
Sabin Sim

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Python basics - Day 06

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Day 6 – Loops (for / range)

Project: Build a “Multiplication Table Generator”

01. Learning Goal

By the end of this lesson, you will be able to:

  • Understand how for loops work in Python
  • Use the range() function for numeric repetition
  • Combine loops with lists, strings, and nested loops
  • Build a program that generates a multiplication table

02. Problem Scenario

You want to repeat actions automatically — for example,

printing every fruit in a basket or generating a multiplication table.

Manually typing each line is inefficient. Loops can automate this process.

03. Step 1 – What is a Loop?

A loop repeats a block of code multiple times.

In Python, there are two main types: for and while.

Today, we focus on for.

04. Step 2 – Basic for Loop

The for loop iterates over iterable objects such as lists, strings, or ranges.

fruits = ["apple", "banana", "grape"]

for f in fruits:
    print(f)
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Output:

apple
banana
grape
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05. Step 3 – Using the range() Function

range() generates a sequence of numbers — commonly used for numeric loops.

# range(stop)
# range(start, stop)
# range(start, stop, step)

for i in range(5):
    print(i)   # 0, 1, 2, 3, 4

for i in range(1, 6):
    print(i)   # 1, 2, 3, 4, 5

for i in range(2, 11, 2):
    print(i)   # 2, 4, 6, 8, 10
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06. Step 4 – Nested Loops

A loop can contain another loop — this is called a nested loop.

for i in range(2, 4):       # 2, 3
    for j in range(1, 4):   # 1, 2, 3
        print(i, "*", j, "=", i * j)
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07. Step 5 – Looping Through Strings

Strings are also iterable, so each character can be processed individually.

for ch in "Python":
    print(ch)
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08. Step 6 – Practice Examples

Example 1: Sum of 1 to 10

total = 0
for i in range(1, 11):
    total += i
print("Sum:", total)
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Example 2: Multiplication Table (2 Times)

for i in range(1, 10):
    print(f"2 x {i} = {2 * i}")
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Example 3: Looping Through a List

names = ["Tom", "Anna", "Sabin"]

for n in names:
    print(f"Hello, {n}!")
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09. Step 7 – Mini Project: Multiplication Table Generator

Now create a program that prints any multiplication table the user requests.

dan = int(input("Enter a number to generate its table: "))

for i in range(1, 10):
    print(f"{dan} x {i} = {dan * i}")
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10. Reflection

You learned how to:

  • Automate repetitive tasks using loops
  • Iterate over lists, strings, and numeric sequences
  • Use nested loops to handle structured patterns
  • Build a functional Multiplication Table Generator

Next → Day 7 – While Loops & Mini Project
Learn how to repeat tasks based on conditions using the while loop.

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