no = 1
top = 5
direction = 1
while no>0:
    print(no,end= ' ')
    if no == top:
        print(no,end=' ')
        direction = -1
    no = no + direction

1 2 3 4 5 5 4 3 2 1 

import random

system_no = random.randint(1,20)

while True:
    guess = int(input("Enter the No. "))
    if guess == system_no:
        print("Hurray!  I got the number!! ")
        break
    elif guess > system_no:
        print("Your guess is too high! ")
    else:
        print("Your guess is too Low! ")

Enter the No. 15
Your guess is too Low! 
Enter the No. 17
Your guess is too Low! 
Enter the No. 19
Hurray!  I got the number!! 

no = int(input("Enter no. "))
max_no = 0
while no>0:
    rem = no%10
    if rem>max_no:
        max_no = rem
    no//=10

print(max_no)

Enter no. 2357
7

no = int(input("Enter no. "))
min_no = 9
while no>0:
    rem = no%10
    if rem<min_no:
        min_no = rem
    no//=10

print(min_no)

Enter no. 2357
2

If the number is even: n=n/2
If the number is odd: n=3n+1.

def even_odd(no):

    while no>0:
        num=no%10
        if num%2==0:
            even=num/2

        else:
            odd=3*num+1

        no=no//10
    return even,odd
no=int(input("Enter the number:"))
even,odd=even_odd(no)
print("even number:",even)
print("odd number:",odd)

Enter the number:12
even number: 1.0
odd number: 4