Loop Patterns

Loops can do more than count numbers.

They can also create shapes and patterns.

Patterns are a great way to practice loops because they help you understand repetition clearly.

What Is a Pattern?

A pattern is something that repeats in a clear order.

For example:

• Stars
• Numbers
• Letters

Print One Line of Stars

for number in range(5):
    print("*")

Output

*
*
*
*
*

This prints one star five times.

Print Stars on One Line

for number in range(5):
    print("*", end="")

Output

*****

end="" tells Python not to move to a new line.

Square Pattern

Use nested loops to print rows and columns.

for row in range(3):
    for star in range(4):
        print("*", end="")
    print()

Output

****
****
****

Number Pattern

for number in range(1, 6):
    print(number)

Output

1
2
3
4
5

Growing Pattern

for row in range(1, 6):
    print("*" * row)

Output

*
**
***
****
*****

Another Growing Number Pattern

for row in range(1, 6):
    print(row * str(row))

Output

1
22
333
4444
55555

Code Along

for row in range(1, 4):
    print("#" * row)

Output

#
##
###

Mini Challenge

Build a triangle pattern.

Steps:

• Use a loop
• Print stars like this:

*
**
***
****

Real World Use Case

Patterns help programmers understand loops. Similar ideas are used in grids, game boards, reports, and layouts.

Quiz

1. What is a pattern?
2. What does end="" do?
3. Why are nested loops useful for patterns?
4. What does "*" * 3 produce?

Assignment

Create a program that prints:

5
55
555
5555
55555

Summary

You learned how loops can create patterns using repetition, nested loops, and string multiplication.