1. Check if a number is even or odd 

num = int(input("Enter a number: "))
if num % 2 == 0:
    print("Even number")
else:
    print("Odd number")

2. Find the largest among three numbers 

a = int(input("Enter first number: "))
b = int(input("Enter second number: "))
c = int(input("Enter third number: "))

if a >= b and a >= c:
    largest = a
elif b >= a and b >= c:
    largest = b
else:
    largest = c

print("The largest number is", largest)

3. Check if a string is a palindrome 

s = input("Enter a string: ")

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

4. Print Fibonacci series up to N terms 

n = int(input("Enter number of terms: "))
a, b = 0, 1
for i in range(n):
    print(a, end=" ")
    a, b = b, a + b

5. Factorial of a number (using loop) 

num = int(input("Enter a number: "))
fact = 1

for i in range(1, num + 1):
    fact *= i

print("Factorial is", fact)

6. Check if a number is prime 

num = int(input("Enter a number: "))

if num < 2:
    print("Not Prime")
else:
    for i in range(2, int(num**0.5)+1):
        if num % i == 0:
            print("Not Prime")
            break
    else:
        print("Prime Number")

7. Reverse a string 

s = input("Enter a string: ")
rev = s[::-1]
print("Reversed string:", rev)

8. Sum of digits of a number 

num = int(input("Enter a number: "))
total = 0
while num > 0:
    total += num % 10
    num = num // 10

print("Sum of digits:", total)

9. Find the second largest number in a list 

numbers = [10, 25, 5, 100, 50]
numbers.sort()
print("Second largest:", numbers[-2])

10. Count vowels in a string 

s = input("Enter a string: ")
vowels = "aeiouAEIOU"
count = 0

for char in s:
    if char in vowels:
        count += 1

print("Number of vowels:", count)

11. sum of digits repeatedly until the number becomes a single digit 

def sum_of_digits(num):
    while num >= 10:
        total = 0
        while num > 0:
            total += num % 10
            num = num // 10
        num = total
    return num

number = int(input("Enter a number: "))
result = sum_of_digits(number)
print("Single digit sum is:", result)

12. Reverse a number (e.g., 123 → 321) 

num = int(input("Enter a number: "))
rev = 0

while num > 0:
    digit = num % 10
    rev = rev * 10 + digit
    num = num // 10

print("Reversed number:", rev)

13. Find sum of elements in a list using sum() and without sum()

Using built-in:

lst = [1, 2, 3, 4, 5]
print("Sum:", sum(lst))

Without built-in:

total = 0
for num in lst:
    total += num
print("Sum:", total)

14. Count frequency of each character in a string 

s = input("Enter a string: ")
freq = {}

for char in s:
    freq[char] = freq.get(char, 0) + 1

for k, v in freq.items():
    print(k, ":", v)