Python For loop and if else Exercises [22 Exercise Programs]

Branching and looping techniques are used in Python to make decisions and control the flow of a program. A good understanding of loops and if-else statements is necessary to write efficient code in Python.

This Python loop exercise contains 22 different coding questions, programs, and challenges to solve using if-else conditions, for loops, the range() function, and while loops.

code solutions are provided for all questions and tested on Python 3.
Use Online Code Editor to solve exercise questions.

Refer to the following tutorials to solve this exercise:

Control flow statements: Use the if-else statements in Python for conditional decision-making.
for loop: Iterate over a sequence of elements such as a list or string.
range() function: Using a for loop with range(), we can repeat an action a specific number of times.
while loop: To execute a code block repeatedly, as long as the condition is True.
Break and Continue: To alter the loop’s execution in a particular manner.
Nested loop: A loop inside another loop is known as a nested loop.

Also Read:

Let us know if you have any alternative solutions. It will help other developers.

Exercise 1: Print first 10 natural numbers using while loop

Help: while loop in Python

Expected output:

Show Solution

# program 1: Print first 10 natural numbers
i = 1
while i <= 10:
    print(i)
    i += 1Code language: Python (python)

Exercise 2: Print the following pattern

Write a Python code to print the following number pattern using a loop.

Refer:

Show Hint

Decide on the row count, which is 5, because the pattern contains five rows.
Run the outer loop 5 times using a for loop and the range() function.
Run the inner loop i+1 times using a for loop and the range() function.
In the first iteration of the outer loop, the inner loop will execute one time.
In the second iteration of the outer loop, the inner loop will execute two times.
In the third iteration of the outer loop, the inner loop will execute three times, and so on, until row 5.
Print the value of j in each iteration of the inner loop (j is the inner loop iterator variable).
Display an empty line at the end of each iteration of the outer loop (an empty line after each row).

Show Solution

print("Number Pattern ")

# Decide the row count. (above pattern contains 5 rows)
row = 5
# start: 1
# stop: row+1 (range never include stop number in result)
# step: 1
# run loop 5 times
for i in range(1, row + 1, 1):
    # Run inner loop i+1 times
    for j in range(1, i + 1):
        print(j, end=' ')
    # empty line after each row
    print("")
Code language: Python (python)

Exercise 3: Calculate sum of all numbers from 1 to a given number

Write a Python program to accept a number from a user and calculate the sum of all numbers from 1 to a given number

For example, if the user entered 10, the output should be 55 (1+2+3+4+5+6+7+8+9+10)

Expected Output:

Enter number 10
Sum is:  55

Refer:

Show Hint

Approach 1: Use for loop and range() function

Create a variable s and initialize it to 0 to store the sum of all numbers.
Use Python 3’s built-in input() function to take input from the user.
Convert the user’s input to an integer type using the int() constructor and save it to a variable n.
Run loop n times using for loop and range() function
In each iteration of the loop, add the current number (i) to the variable s.
Use the print() function to display the value of the variable s on the screen.

Approach 2: Use the built-in function sum(). The sum() function calculates the addition of all numbers from 1 to a given number.

Show Solution

Solution 1: Using for loop and range() function

# s: store sum of all numbers
s = 0
n = int(input("Enter number "))
# run loop n times
# stop: n+1 (because range never include stop number in result)
for i in range(1, n + 1, 1):
    # add current number to sum variable
    s += i
print("\n")
print("Sum is: ", s)
Code language: Python (python)

Solution 2: Using the built-in function sum()

n = int(input("Enter number "))
# pass range of numbers to sum() function
x = sum(range(1, n + 1))
print('Sum is:', x)
Code language: Python (python)

Exercise 4: Print multiplication table of a given number

Given:

num = 2Code language: Python (python)

Expected output is:

Show Hint

You can use a simple for loop to generate the multiplication table for a specific number.

Set n = 2.
Use for loop to iterate the first 10 natural numbers (From 1 to 10)
In each iteration, multiply the current number by 2 ( p = n*i). Now print p

Also See: Create Multiplication Table in Python

Show Solution

n = 2
# stop: 11 (because range never include stop number in result)
# run loop 10 times
for i in range(1, 11, 1):
    # 2 *i (current number)
    product = n * i
    print(product)Code language: Python (python)

Exercise 5: Display numbers from a list using a loop

Write a Python program to display only those numbers from a list that satisfy the following conditions

The number must be divisible by five
If the number is greater than 150, then skip it and move to the following number
If the number is greater than 500, then stop the loop

Given:

numbers = [12, 75, 150, 180, 145, 525, 50]Code language: Python (python)

Expected output:

75
150
145

Refer: break and continue in Python

Show Hint

Use a for loop to iterate through each item in the list.
Use a break statement to exit the loop if the current number is greater than 500.
Use the continue statement to skip the current number and move to the next if the current number is greater than 150.
Use the condition number % 5 == 0 to check if the number is divisible by 5.

Show Solution

numbers = [12, 75, 150, 180, 145, 525, 50]
# iterate each item of a list
for item in numbers:
    if item > 500:
        break
    elif item > 150:
        continue
    # check if number is divisible by 5
    elif item % 5 == 0:
        print(item)Code language: Python (python)

Exercise 6: Count the total number of digits in a number

Write a Python program to count the total number of digits in a number using a while loop.

For example, the number is 75869, so the output should be 5.

Show Hint

Set counter = 0
Run while loop till number != 0
In each iteration of a loop
- Reduce the last digit from the number using floor division ( number = number // 10)
- Increment counter by 1
print counter after loop execution is completed

Show Solution

num = 75869
count = 0
while num != 0:
    # floor division
    # to reduce the last digit from number
    num = num // 10

    # increment counter by 1
    count = count + 1
print("Total digits are:", count)Code language: Python (python)

Exercise 7: Print the following pattern

Write a Python program to print the reverse number pattern using a for loop.

Refer: Print patterns in Python

Show Hint

Setting the row value to 5 is crucial, as the pattern we’re working with has five rows.
Using a for loop and the range() function, create an outer loop that iterates through numbers from 1 to 5.
The outer loop controls the number of iterations of the inner loop. For each outer loop iteration, the number of inner loop iterations is reduced by i, the outer loop’s current number.
In each iteration of the inner loop, print the iterator variable of the inner loop (j).

Note:

In the first iteration of the outer loop, the inner loop executes five times.
In the second iteration of the outer loop, the inner loop executes four times.
In the last iteration of the outer loop, the inner loop will execute only once.

Show Solution

n = 5
k = 5
for i in range(0,n+1):
    for j in range(k-i,0,-1):
        print(j,end=' ')
    print()Code language: Python (python)

Exercise 8: Print list in reverse order using a loop

Given:

list1 = [10, 20, 30, 40, 50]Code language: Python (python)

Expected output:

Show Hint

Approach 1: Use the built-in function reversed() to reverse the list

Approach 2: Use for loop and the len() function

Get the size of a list using the len(list1) function.
Use a for loop and reversed(range()) to iterate through index numbers in reverse order, starting from length-1 down to 0. In each iteration, i will be reduced by 1.
In each iteration, print list items using list1[i]. i is the current value of the index.

Show Solution

Solution 1: Using a reversed() function and for loop

list1 = [10, 20, 30, 40, 50]
# reverse list
new_list = reversed(list1)
# iterate reversed list
for item in new_list:
    print(item)
Code language: Python (python)

Solution 2: Using for loop and the len() function

list1 = [10, 20, 30, 40, 50]
# get list size
# len(list1) -1: because index start with 0
# iterate list in reverse order
# star from last item to first
size = len(list1) - 1
for i in range(size, -1, -1):
    print(list1[i])
Code language: Python (python)

Exercise 9: Display numbers from -10 to -1 using for loop

Expected output:

-10
-9
-8
-7
-6
-5
-4
-3
-2
-1

See: Reverse range

Show Solution

for num in range(-10, 0, 1):
    print(num)Code language: Python (python)

Exercise 10: Display a message “Done” after the successful execution of the for loop

For example, the following loop will execute without any error.

Given:

for i in range(5):
    print(i)Code language: Python (python)

Expected output:

0
1
2
3
4
Done!

Show Hint

Python allows us to use an else block with a for loop like the if statement. The loop can have the else block, which will be executed when it terminates normally. See else block in for loop.

Show Solution

for i in range(5):
    print(i)
else:
    print("Done!")Code language: Python (python)

Exercise 11: Print all prime numbers within a range

Note: A Prime Number is a number that can only be divided by itself and 1 without remainders (e.g., 2, 3, 5, 7, 11)

A Prime Number is a natural number greater than 1 that cannot be made by multiplying other whole numbers.

Examples:

6 is not a prime number because it can be made by 2×3 = 6
37 is a prime number because no other whole numbers multiply to make it.

Given:

# range
start = 25
end = 50Code language: Python (python)

Expected output:

Prime numbers between 25 and 50 are:
29
31
37
41
43
47

See: Python Programs to Find Prime Numbers within a Range

Show Hint

Think about what defines a prime number. Then, consider how you can check that property for each number within the given range using a loop. You might need another loop inside to help with the check.

Iterate through each number in the given range.
For each number, assume it’s prime initially.
Check for divisibility from 2 up to the square root of the number.
If divisible by any number in this range, it’s not prime.
If the inner loop completes without finding a divisor and the number is greater than 1, then it’s prime.
Print the numbers identified as prime.
Remember to handle numbers less than or equal to 1.

Show Solution

start = 25
end = 50
print("Prime numbers between", start, "and", end, "are:")

for num in range(start, end + 1):
    # all prime numbers are greater than 1
    # if number is less than or equal to 1, it is not prime
    if num > 1:
        for i in range(2, num):
            # check for factors
            if (num % i) == 0:
                # not a prime number so break inner loop and
                # look for next number
                break
        else:
            print(num)Code language: Python (python)

Exercise 12: Display Fibonacci series up to 10 terms

Have you ever wondered about the Fibonacci Sequence? It’s a series of numbers in which the next number is found by adding up the two numbers before it. The first two numbers are 0 and 1.

For example, 0, 1, 1, 2, 3, 5, 8, 13, 21. The next number in this series is 13 + 21 = 34.

Expected output:

Fibonacci sequence:
0  1  1  2  3  5  8  13  21  34

Refer: Generate Fibonacci Series in Python

Show Hint

Set num1 = 0 and num2 = 1 (first two numbers of the sequence)
Run the loop 10 times
In each iteration
- print num1 as the current number of the sequence
- Add the last two numbers to get the following number result = num1 + num2
- update values of num1 and num2. Set num1 = num2 and num2 = result

Show Solution

# first two numbers
num1, num2 = 0, 1

print("Fibonacci sequence:")
# run loop 10 times
for i in range(10):
    # print next number of a series
    print(num1, end="  ")
    # add last two numbers to get next number
    res = num1 + num2

    # update values
    num1 = num2
    num2 = resCode language: Python (python)

Exercise 13: Find the factorial of a given number

Write a Python program to use for loop to find the factorial of a given number.

The factorial (symbol: !) means multiplying all numbers from the chosen number down to 1.

For example, a factorial of 5! is 5 × 4 × 3 × 2 × 1 = 120

Expected output:

Show Hint

Set variable factorial = 1 to store the factorial of a given number
Iterate numbers starting from 1 to the given number n using for loop and range() function. (here, the loop will run five times because n is 5)
In each iteration, multiply the factorial by the current number and assign it again to a factorial variable (factorial = factorial *i)
After the loop completes, print factorial

Show Solution

num = 5
factorial = 1
if num < 0:
    print("Factorial does not exist for negative numbers")
elif num == 0:
    print("The factorial of 0 is 1")
else:
    # run loop 5 times
    for i in range(1, num + 1):
        # multiply factorial by current number
        factorial = factorial * i
    print("The factorial of", num, "is", factorial)Code language: Python (python)

Exercise 14: Reverse a integer number

Given:

76542

Expected output:

24567

See: Python Programs to Reverse an Integer Number

Show Hint

Initialize a variable to store the reversed number (set it to 0 initially).
Use a while loop that continues as long as the original number is greater than 0.
Inside the loop:
- Extract the last digit of the original number using the modulo operator (% 10).
- Update the reversed number: multiply it by 10 and then add the extracted last digit.
- Update the original number by integer division (// 10) to remove the last digit.
After the loop finishes, the reversed number variable will hold the reversed integer.

Show Solution

num = 76542
reverse_number = 0
print("Given Number ", num)
while num > 0:
    reminder = num % 10
    reverse_number = (reverse_number * 10) + reminder
    num = num // 10
print("Revere Number ", reverse_number)Code language: Python (python)

Exercise 15: Print elements from a given list present at odd index positions

Given:

my_list = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]Code language: Python (python)

Note: The list index always starts at 0

Expected output:

20 40 60 80 100

Show Hint

Use list slicing. List slicing in Python is a powerful way to extract a portion (a sublist) of a list based on a specified range of indices. It allows you to create new lists containing elements from a specific starting point up to (but not including) a specific ending point in the original list.

Show Solution

my_list = [10, 20, 30, 40, 50, 60, 70, 80, 90, 100]
# stat from index 1 with step 2( means 1, 3, 5, an so on)
for i in my_list[1::2]:
    print(i, end=" ")Code language: Python (python)

Exercise 16: Calculate the cube of all numbers from 1 to a given number

Write a Python program to print the cube of all numbers from 1 to a given number

Given:

input_number = 6

Expected output:

Current Number is : 1  and the cube is 1
Current Number is : 2  and the cube is 8
Current Number is : 3  and the cube is 27
Current Number is : 4  and the cube is 64
Current Number is : 5  and the cube is 125
Current Number is : 6  and the cube is 216

Show Hint

Iterate numbers from 1 to n using for loop and range() function
In each iteration of a loop, calculate the cube of a current number (i) by multiplying itself three times (cube = i * i* i)

Show Solution

input_number = 6
for i in range(1, input_number + 1):
    print("Current Number is :", i, " and the cube is", (i * i * i))Code language: Python (python)

Exercise 17: Find the sum of a series of a number up to n terms

Write a program to calculate the sum of this series up to n terms. For example, if the number is 2 and the number of terms is 5, then the series will be 2+22+222+2222+22222=2469

Given:

# number of terms
num = 2
terms = 5Code language: Python (python)

Expected output:

Show Hint

Initialize a variable sum with the base number.
Initialize a variable current_term with the base number.
Loop n-1 times (since the first term is already accounted for in the initialization).
Inside the loop:
- Update current_term: multiply it by 10 and add the base number.
- Add the updated current_term to the sum.
After the loop, the sum variable will hold the result.

Show Solution

terms = 5
# first number of sequence
num = 2
sum_seq = 0

# run loop n times
for i in range(0, terms):
    print(num, end="+")
    sum_seq += num
    # calculate the next term
    num = num * 10 + 2
print("\nSum of above series is:", sum_seq)Code language: Python (python)

Exercise 18: Print the following pattern

Write a program to print the following start pattern using the for loop

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

Refer: Print Patterns In Python

Show Hint

Use two for loops. The first loop will print the upper pattern, and the second loop will print the lower pattern.

First Pattern:

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

Second Pattern:

* * * * 
* * * 
* * 
*

Show Solution

rows = 5
for i in range(0, rows):
    for j in range(0, i + 1):
        print("*", end=' ')
    print("\r")

for i in range(rows, 0, -1):
    for j in range(0, i - 1):
        print("*", end=' ')
    print("\r")
Code language: Python (python)

Exercise 19: Print Full Multiplication Table

The multiplication table from 1 to 10 is a table that shows the products of numbers from 1 to 10.

Write a code to generates a complete multiplication table for numbers 1 through 10.

Given:

multiplication table of: 1
 1 2 3 4 5 6 7 8 9 10
multiplication table of: 2
 2 4 6 8 10 12 14 16 18 20
multiplication table of: 3
 3 6 9 12 15 18 21 24 27 30
...
multiplication table of: 10
 10 20 30 40 50 60 70 80 90 100

See: Create Multiplication Table in Python

Show Hint

Use nested loop, where one loop is placed inside another.

The outer loop iterates through the rows (numbers 1 to 10).
The inner loop iterates through the columns (numbers 1 to 10) to calculate and display the product of the numbers.

Show Solution

# Full multiplication table from 1 to 10
for i in range(1, 11):
  print('multiplication table of:', i)
  for j in range(1, 11):
    print(f" {i * j}", end="")
  print() # Move to the next line after each rowCode language: Python (python)

Exercise 20: Print the alternate numbers pattern

Pattern:

1  
2 3  
4 5 6  
7 8 9 10  
11 12 13 14 15

Show Hint

You need to use two nested loop inside a single loop.

Think about how the numbers are arranged in each row and how that arrangement changes from one row to the next. Consider these points:

Row Number: Notice that the behavior of the numbers in a row depends on whether the row number is odd or even.
Number of Elements per Row: The first row has one number, the second has two, the third has three, and so on. The ith row contains i numbers.
Odd Rows: In odd-numbered rows (1st, 3rd, 5th, etc.), the numbers are printed in increasing order.
Even Rows: In even-numbered rows (2nd, 4th, etc.), the numbers are printed in decreasing order.
Starting Number: You need to keep track of the starting number for each row. Observe how the last number of one row relates to the first number of the next row.

Try to use these observations to build your logic row by row. You’ll likely need a loop that iterates through the rows, and inside that loop, you’ll have different logic based on whether the current row is odd or even.

Show Solution

def print_alternate_pattern(rows):
    num = 1
    for i in range(1, rows + 1):
        if i % 2 != 0: # Odd row: increasing order
            for x in range(num, num + i):
              print(x, end=' ')
            print() # to diaply next row of number on new line
        else: # Even row: decreasing order
            for y in range(num + i - 1, num - 1, -1):
              print(y, end=' ')
            print() # # to diaply next row of number on new line
        num += i

# Call the function to print the pattern with a specified number of rows
print_alternate_pattern(5)Code language: Python (python)

Exercise 21: Flatten a nested list using loops

Write a program to flatten a nested list using loops.

Given:

nested_list = [1, [2, 3], [4, 5, 6], 7, [8, 9]]

# write function 'flatten_list' to flatten a nested list
flattened = flatten_list(nested_list)
print("Flattened list:", flattened)

# Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]Code language: Python (python)

Show Hint

You need to use nested loop ( a loop inside another loop)

Write Outer Loop:
- Iterates over each element in the input nested_list.
Write Inner Loop:
- Check If the element is a list, iterate through the sublist and append each item to flat_list.
- Otherwise, append the element directly to flat_list.
After processing all elements, return the flattened list.

See: Python isinstance()

Show Solution

def flatten_list(nested_list):
    
    flat_list = []  # Initialize an empty list to store the flattened elements

    # Iterate through each element in the list
    for element in nested_list:
        if isinstance(element, list):  # Check if the element is a list
            for item in element:  # If so, iterate through the inner list
                flat_list.append(item)
        else:
            flat_list.append(element)  # If not a list, add the element directly

    return flat_list

# Example usage
nested_list = [1, [2, 3], [4, 5, 6], 7, [8, 9]]
flattened = flatten_list(nested_list)
print("Flattened list:", flattened)

# Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]Code language: Python (python)

Exercise 22: Find largest and smallest digit in a number

Write a program in Python identifies the digit with the highest value and the digit with the lowest value within that number.

Input:

num1 = 9876543210
num2 = -5082Code language: Python (python)

Output:

Largest digit in 9876543210: 9
Smallest digit in 987654321: 1

Largest digit in -5082: 8
Smallest digit in -5082: 0

Show Hint

Get Number and treat the Number as a Sequence of Digits.
Handle the sign (maybe take the absolute value).
Convert the (absolute) number to a string.
Initialize variables to store the largest and smallest digits (perhaps with the first digit of the string converted to an integer).
Loop through the remaining characters of the string (starting from the second character).
Inside the loop:
- Convert the current character to an integer.
- Compare it with the current largest and smallest, updating if necessary.
Return or print the largest and smallest digits.

Show Solution

def find_largest_smallest_digit(number):
 
  if number == 0:
    print("The number is zero. Largest and smallest digit is 0.")
    return 0, 0

  s_number = str(abs(number))  # Convert to string and handle negative numbers
  largest_digit = int(s_number[0])
  smallest_digit = int(s_number[0])

  for digit in s_number[1:]:
    digit_int = int(digit)
    if digit_int > largest_digit:
      largest_digit = digit_int
    if digit_int < smallest_digit:
      smallest_digit = digit_int

  return largest_digit, smallest_digit

# Example usage:

num1 = 9876543210
largest1, smallest1 = find_largest_smallest_digit(num1)
if largest1 is not None:
  print(f"Largest digit in {num1}: {largest1}")
  print(f"Smallest digit in {num1}: {smallest1}")

num2 = -5082
largest2, smallest2 = find_largest_smallest_digit(num2)
if largest2 is not None:
  print(f"Largest digit in {num2}: {largest2}")
  print(f"Smallest digit in {num2}: {smallest2}")Code language: Python (python)

Python if else, for loop, and range() Exercises with Solutions

Table of contents

Exercise 1: Print first 10 natural numbers using while loop

Exercise 2: Print the following pattern

Exercise 3: Calculate sum of all numbers from 1 to a given number

Exercise 4: Print multiplication table of a given number

Exercise 5: Display numbers from a list using a loop

Exercise 6: Count the total number of digits in a number

Exercise 7: Print the following pattern

Exercise 8: Print list in reverse order using a loop

Exercise 9: Display numbers from -10 to -1 using for loop

Exercise 10: Display a message “Done” after the successful execution of the for loop

Exercise 11: Print all prime numbers within a range

Exercise 12: Display Fibonacci series up to 10 terms

Exercise 13: Find the factorial of a given number

Exercise 14: Reverse a integer number

Exercise 15: Print elements from a given list present at odd index positions

Exercise 16: Calculate the cube of all numbers from 1 to a given number

Exercise 17: Find the sum of a series of a number up to n terms

Exercise 18: Print the following pattern

Exercise 19: Print Full Multiplication Table

Exercise 20: Print the alternate numbers pattern

Exercise 21: Flatten a nested list using loops

Exercise 22: Find largest and smallest digit in a number

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