Nested while loops in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print numbers from 1 to 3 using a while loop.

Python

i = 1
while i [1] 3:
    print(i)
    i += 1

Drag options to blanks, or click blank then click option'

A==

B>

C<

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of a comparison operator for the loop condition.

Using '>' which would never start the loop since i=1.

The condition i <= 3 makes the loop run while i is less than or equal to 3, printing 1, 2 and 3.

2fill in blank

medium

Complete the code to print a 3x3 grid of stars using nested while loops.

Python

row = 0
while row < 3:
    col = 0
    while col [1] 3:
        print('*', end='')
        col += 1
    print()
    row += 1

Drag options to blanks, or click blank then click option'

A>

B<=

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' causes 4 stars per row.

Using '==' only runs the loop once.

The inner loop runs while col < 3 to print 3 stars per row.

3fill in blank

hard

Fix the error in the nested while loops to print numbers 1 to 3 in each row for 3 rows.

Python

row = 1
while row <= 3:
    col = 1
    while col [1] 3:
        print(col, end=' ')
        col += 1
    print()
    row += 1

Drag options to blanks, or click blank then click option'

A<=

B<

C>=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' excludes the number 3 from printing.

Using '==' only runs the loop once.

The inner loop should run while col <= 3 to include 3 in the output.

4fill in blank

hard

Fill both blanks to create a nested while loop that prints a triangle of stars with 4 rows.

Python

row = 1
while row [1] 4:
    col = 1
    while col [2] row:
        print('*', end='')
        col += 1
    print()
    row += 1

Drag options to blanks, or click blank then click option'

A<=

B<

C>

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' for outer loop causes only 3 rows.

Using '>=' or '>' causes loops not to run as expected.

The outer loop runs while row <= 4 to print 4 rows.
The inner loop runs while col <= row to print stars increasing each row.

5fill in blank

hard

Fill all three blanks to create nested while loops that print a 3x3 grid of numbers counting from 1 to 9.

Python

num = 1
row = 1
while row [1] 3:
    col = 1
    while col [2] 3:
        print(num, end=' ')
        num [3] 1
        col += 1
    print()
    row += 1

Drag options to blanks, or click blank then click option'

A<=

B<

C+=

D-=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' for outer loop excludes last row.

Using '-=' decreases the number instead of increasing.

Using '>=' or '>' causes loops not to run.

The outer loop runs while row <= 3 to print 3 rows.
The inner loop runs while col <= 3 to print 3 columns.
num += 1 increases the number each time.