Level: Beginner → Intermediate transition
Focus: Logic, loops, conditions, math reasoning, small algorithms

Exercise 1 — Sum of the First N Natural Numbers

Objective: Practice loops and accumulation logic.
Task:
Ask the user for a number N and compute the sum:
1 + 2 + 3 + … + N

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

total = 0
for i in range(1, n + 1):
    total += i

print("Sum of first", n, "natural numbers is:", total)

Exercise 2 — Find the Second Largest Number in a List

Objective: Sorting logic + list manipulation.
Task:
Given a list of numbers, print the second largest value without using max() twice.

 numbers = [10, 5, 8, 20, 3, 20]

unique = list(set(numbers))      # remove duplicates
unique.sort(reverse=True)        # sort descending

if len(unique) < 2:
    print("No second largest number.")
else:
    print("Second largest number is:", unique[1])

Exercise 3 — Count How Many Times a Value Appears

Objective: Frequency counting algorithm.
Task:
Ask the user for a list and a target number → count how many times it appears.

 nums_str = input("Enter numbers separated by spaces: ")
target = input("Enter the value to count: ")

numbers = nums_str.split()
count = 0

for n in numbers:
    if n == target:
        count += 1

print("The value", target, "appears", count, "time(s).")

Exercise 4 — Palindrome Checker

Objective: String manipulation + logic.
Task:
Write a program that checks if a given word is a palindrome (same forwards and backwards).

 word = input("Enter a word: ")
clean = word.lower()

if clean == clean[::-1]:
    print("Palindrome")
else:
    print("Not a palindrome")

Exercise 5 — Find All Divisors of a Number

Objective: Use loops to compute divisors.
Task:
Ask the user for a number and print all integers that divide it evenly.

 num = int(input("Enter a positive integer: "))

print("Divisors of", num, "are:")
for i in range(1, num + 1):
    if num % i == 0:
        print(i)

Exercise 6 — FizzBuzz

Objective: Classic programming challenge combining modulus and conditions.
Task:
Print numbers from 1 to 50:

• “Fizz” if divisible by 3
• “Buzz” if divisible by 5
• “FizzBuzz” if divisible by both

 for i in range(1, 51):
    if i % 3 == 0 and i % 5 == 0:
        print("FizzBuzz")
    elif i % 3 == 0:
        print("Fizz")
    elif i % 5 == 0:
        print("Buzz")
    else:
        print(i)

Exercise 7 — Compute the Factorial of a Number

Objective: Loop-based algorithm + multiplication accumulation.
Task:
Ask the user for a number N and compute N! (factorial).

 n = int(input("Enter a non-negative integer: "))

factorial = 1
for i in range(1, n + 1):
    factorial *= i

print(str(n) + "! =", factorial)

Exercise 8 — Remove All Even Numbers from a List

Objective: Filtering algorithm.
Task:
Given a list, build a new list containing only the odd numbers.

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

odds = []
for n in numbers:
    if n % 2 != 0:
        odds.append(n)

print("Original list:", numbers)
print("Odd numbers only:", odds)

Exercise 9 — Find the Longest Word in a Sentence

Objective: String processing + iteration.
Task:
Ask the user for a sentence and print the longest word.

 sentence = input("Enter a sentence: ")
words = sentence.split()

longest = ""
for w in words:
    if len(w) > len(longest):
        longest = w

print("Longest word is:", longest)
print("Length:", len(longest))

Exercise 10 — Generate the First N Fibonacci Numbers

Objective: Sequence generation + iterative thinking.
Task:
Ask the user for a number N and print the first N numbers of the Fibonacci sequence.

 n = int(input("How many Fibonacci numbers? "))

a, b = 0, 1

for _ in range(n):
    print(a)
    a, b = b, a + b