Problems on Loops

1. Print Numbers from 1 to 10

Problem: Print numbers from 1 to 10.
Example Output:

1 2 3 4 5 6 7 8 9 10

2. Sum of First N Natural Numbers

Problem: Calculate the sum of numbers from 1 to N.
Example Input: N = 5
Output: 15

3. Print Each Character in a String

Problem: Print each character of a string.
Input: "Python"
Output:

P y t h o n

4. Print Even Numbers from 1 to 20

Problem: Print only even numbers between 1 and 20.
Output:

2 4 6 8 10 12 14 16 18 20

5. Print List Elements Using Loop

Problem: Display all elements from a list using a loop.
Input: ["apple", "banana", "cherry"]
Output:

apple
banana
cherry

6. Reverse Counting from 10 to 1

Problem: Print numbers from 10 down to 1.
Output:

10 9 8 7 6 5 4 3 2 1

7. Print Multiplication Table of a Number

Problem: Take a number and print its multiplication table up to 10.
Input: 3
Output:

3 x 1 = 3
3 x 2 = 6
...
3 x 10 = 30

8. Find the Factorial of a Number

Problem: Find the factorial of a given number.
Input: 5
Output: 120

9. Print Digits of a Number (Using while loop)

Problem: Display each digit of a number separately.
Input: 1234
Output:

10. FizzBuzz

Problem: Print numbers 1–20 but:

Print “Fizz” if divisible by 3
Print “Buzz” if divisible by 5
Print “FizzBuzz” if divisible by both
Output Example:

1
2
Fizz
4
Buzz
...
FizzBuzz

11. Sum of Even Numbers in a List

Problem: Calculate the sum of all even numbers in a list.
Input: [1, 4, 7, 10, 12]
Output: 26

12. Count Vowels in a String

Problem: Count the number of vowels in a given string.
Input: "Python is fun"
Output: 4

13. Print Numbers Divisible by 4 and 6

Problem: Print numbers from 1 to 50 divisible by both 4 and 6.
Output:

12 24 36 48

14. Cumulative Sum of List

Problem: Print cumulative sum at each step from a list.
Input: [2, 5, 3, 7]
Output:

2 7 10 17

15. Print Multiples of 3 and 5

Problem: Print numbers between 1–50 divisible by 3 or 5.
Output Example:

3 5 6 9 10 12 ... 45 48 50

16. Reverse a String

Problem: Print a string in reverse.
Input: "Python"
Output: nohtyP

17. Find Numbers with Even Digits

Problem: Print numbers from 1–100 that have an even number of digits.
Output Example:

10 11 12 ... 99

18. Find the Maximum Number in a List

Problem: Find the largest number in a list.
Input: [5, 12, 3, 21, 7]
Output: 21

19. Count Digits and Letters in a String

Problem: Count letters and digits separately in a string.
Input: "Python3.8"
Output:

Letters: 6
Digits: 2

20. Fibonacci Numbers Less Than N

Problem: Print all Fibonacci numbers less than a given number N.
Input: N = 20
Output:

0 1 1 2 3 5 8 13

21. Print Odd Numbers in a List

Problem: Print all odd numbers from a given list.
Input: [2, 7, 4, 9, 12, 15]
Output: 7 9 15

22. Count Uppercase and Lowercase Letters

Problem: Count the number of uppercase and lowercase letters in a string.
Input: "Python Is Fun"
Output:

Uppercase: 3
Lowercase: 8

23. Print Squares of Numbers

Problem: Print squares of numbers from 1 to N.
Input: N = 5
Output:

1 4 9 16 25

24. Print Cubes of Numbers in a List

Problem: Print cubes of numbers from a given list.
Input: [1, 2, 3, 4]
Output:

1 8 27 64

25. Print Numbers Divisible by 7 but Not by 5

Problem: Print numbers from 1–100 divisible by 7 but not by 5.
Output Example:

7 14 21 28 ... 91 98

26. Print Factorials of Numbers in a List

Problem: Print factorial of each number in a list.
Input: [3, 4, 5]
Output:

6 24 120

27. Count Words in a Sentence

Problem: Count the number of words in a given sentence.
Input: "Python is fun to learn"
Output: 5

28. Print Prime Numbers from 1 to N

Problem: Print all prime numbers from 1 to N.
Input: N = 20
Output:

2 3 5 7 11 13 17 19

29. Sum of Digits of Numbers in a List

Problem: Print sum of digits for each number in a list.
Input: [12, 34, 56]
Output: 3 7 11

30. Check Palindrome Numbers in a List

Problem: Print all numbers from a list that are palindromes.
Input: [121, 123, 454, 567, 787]
Output: 121 454 787