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Looping Structures

[Set – 1]

1. Write a Python program to print the numbers from 1 to 10 using a for loop. Solution

for num in range(1, 11):
    print(num)

2. Write a Python program to print the numbers from 20 to 1 using a while loop. Solution

num = 20
while num >= 1:
    print(num)
    num -= 1

3. Write a program to print even numbers from 1 to 10. Solution

for num in range(2, 11, 2):
    print(num)

4. Write a program that prompts the user to enter a number n and prints all the numbers from 1 to n. Solution

n = int(input("Enter a number: "))
for num in range(1, n + 1):
    print(num)

5. Write a program that prompts the user to enter a number n, and then prints all the odd numbers between 1 and n. Solution

n = int(input("Enter a number: "))
for num in range(1, n + 1, 2):
    print(num)

6. Write a program that prints 'Happy Birthday!' five times on screen. Solution

for i in range(5):
    print("Happy Birthday!")

7. Write a program that takes a number n as input from the user and generates the first n terms of the series formed by squaring the natural numbers.

Sample output
Enter a number: 6
The first 6 terms of the series are:
1 4 9 16 25 36 Solution

n = int(input("Enter a number: "))
print("The first", n, "terms of the series are:")
for i in range(1, n + 1):
    term = i ** 2
    print(term, end=" ")

8. Write a program that prompts the user to input a number and prints its multiplication table. Solution

9. Write a Python program to print the first 8 terms of an arithmetic progression starting with 3 and having a common difference of 4.
The program should output the following sequence:
3 7 11 15 19 23 27 31 Solution

start = 3
difference = 4
term = start
           
for i in range(8):
    print(term, end=" ")
    term += difference

10. Write a Python program to print the first 6 terms of a geometric sequence starting with 2 and having a common ratio of 3.
The program should output the following sequence:
2 6 18 54 162 486 Solution

start = 2
ratio = 3
term = start
for i in range(6):
    print(term, end=" ")
    term *= ratio

11. Write a program that asks the user for a positive integer value. The program should calculate the sum of all the integers from 1 up to the number entered. For example, if the user enters 20, the loop will find the sum of 1, 2, 3, 4, ... 20. Solution

12. write a program that takes a positive integer N as input and calculates the sum of the reciprocals of all numbers from 1 up to N. The program should display the final sum. Output of the program should be like:
Enter a positive integer: 5
The sum of reciprocals from 1 to 5 is: 2.28 Solution

N = int(input("Enter a positive integer: "))
sum_reciprocals = 0.0

for num in range(1, N + 1):
    sum_reciprocals += 1 / num

print("The sum of reciprocals from 1 to", N, "is:", "{:.2f}".format(sum_reciprocals))

13. Write a program that prompts the user to enter a number and repeats this process 5 times. The program should accumulate the numbers entered and then display the final running total.

Sample Output:
Enter a number: 10
Enter a number: 15
Enter a number: 35
Enter a number: 40
Enter a number: 50
The final running total is: 150 Solution

total = 0

for i in range(5):
    number = int(input("Enter a number: "))
    total += number

print("The final running total is:", total)

14. Write a program that prompts the user to enter a positive integer and calculates its factorial. The factorial of a positive integer 'n' is denoted as 'n!' and is calculated by multiplying all the integers from 1 to 'n' together. For example, the factorial of 5 (denoted as 5!) is calculated as 1 x 2 x 3 x 4 x 5.

The program should display the factorial value if the input is a positive number, or display a message stating that the factorial does not exist for negative numbers. Additionally, for an input of zero, the program should output that the factorial of 0 is 1. Solution

15. Write a Python program that prompts the user to enter a base number and an exponent, and then calculates the power of the base to the exponent. The program should not use the exponentiation operator (**) or the math.pow() function. The program should handle both positive and negative exponents. Solution