While Loop

The while loop is used to repeat a block of code as long as a given condition is true. It’s a fundamental tool for creating loops when the number of iterations isn’t predetermined. Here are some beginner-friendly exercises to practice the while loop.

Practice Problems

Problems Index

Print numbers from 1 to 10 using a while loop.
Calculate the factorial of a given number.
Input numbers continuously and stop when a negative number is entered. Then, print their sum.
Print the first n even numbers.
Reverse the digits of a given number.
Count the number of digits in an integer.
Print the Fibonacci series up to n terms.
Find the greatest common divisor (GCD) of two numbers using repeated subtraction.
Input marks until a valid score (0–100) is entered, then details it.
Continuously take input using while True and exit the loop only if “stop” is entered.

Try It Yourself

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Output:

Solutions

Print numbers from 1 to 10 using a while loop.

Show Code

i = 1
while i <= 10:
    print(i)
    i += 1

Calculate the factorial of a given number.

Show Code

num = int(input("Enter a number: "))
factorial = 1
while num > 0:
    factorial *= num
    num -= 1
print("Factorial is:", factorial)

Input numbers continuously and stop when a negative number is entered. Then, print their sum.

Show Code

total = 0
while True:
    num = int(input("Enter a number: "))
    if num < 0:
        break
    total += num
print("Sum of numbers:", total)

Print the first n even numbers.

Show Code

n = int(input("Enter how many even numbers to print: "))
count = 0
num = 2
while count < n:
    print(num)
    num += 2
    count += 1

Reverse the digits of a given number.

Show Code

num = int(input("Enter a number: "))
reverse = 0
while num > 0:
    digit = num % 10
    reverse = reverse * 10 + digit
    num //= 10
print("Reversed number:", reverse)

Count the number of digits in an integer.

Show Code

num = int(input("Enter a number: "))
count = 0
while num > 0:
    num //= 10
    count += 1
print("Number of digits:", count)

Print the Fibonacci series up to n terms.

Show Code

n = int(input("Enter the number of terms: "))
a, b = 0, 1
count = 0
while count < n:
    print(a)
    a, b = b, a + b
    count += 1

Find the greatest common divisor (GCD) of two numbers using repeated subtraction.

Show Code

a = int(input("Enter the first number: "))
b = int(input("Enter the second number: "))
while a != b:
    if a > b:
        a -= b
    else:
        b -= a
print("GCD is:", a)

Input marks until a valid score (0–100) is entered, then details it.

Show Code

while True:
    marks = int(input("Enter marks (0-100): "))
    if 0 <= marks <= 100:
        print("Valid marks:", marks)
        break
    else:
        print("Invalid input. Try again.")

Continuously take input using while True and exit the loop only if “stop” is entered.

Show Code

while True:
    text = input("Enter something (type 'stop' to exit): ")
    if text.lower() == "stop":
        print("Exiting the loop.")
        break
    print("You entered:", text)

For Loop Nested Loops