Course

Advanced

Measure the Elapsed Time in Python Represent enum Create a Countdown Timer Convert Bytes to a String

Introduction

Print Hello world!Add Two Numbers Find the Square Root Calculate the Area of a Triangle Solve Quadratic Equation Swap Two Variables Generate a Random Number Convert Kilometers to Miles Convert Celsius To Fahrenheit Print Output Without a Newline

Object Oriented

Get the Class Name of an Instance Differentiate Between type() and isinstance()

Decision Making and Loops

Check if a Number is Positive, Negative or 0 Check if a Number is Odd or Even Check Leap Year Find the Largest Among Three Numbers Check Prime Number Print all Prime Numbers in an Interval Find the Factorial of a Number Display the multiplication Table Print the Fibonacci sequence Check Armstrong Number Find Armstrong Number in an Interval Find the Sum of Natural Numbers Create Pyramid Patterns Iterate Over Dictionaries Using for Loop Reverse a Number Compute the Power of a Number

Functions

Display Powers of 2 Using Anonymous Function Find Numbers Divisible by Another Number Convert Decimal to Binary, Octal and Hexadecimal Find ASCII Value of Character Find HCF or GCD Find LCM Find the Factors of a Number Make a Simple Calculator Shuffle Deck of Cards Display Calendar Display Fibonacci Sequence Using Recursion Find Sum of Natural Numbers Using Recursion Find Factorial of Number Using Recursion Convert Decimal to Binary Using Recursion Return Multiple Values From a Function

Native Datatypes

Add Two Matrices Transpose a Matrix Multiply Two Matrices Check Whether a String is Palindrome or Not Remove Punctuations From a String Sort Words in Alphabetic Order Illustrate Different Set Operations Count the Number of Each Vowel Merge Two Dictionaries Access Index of a List Using for Loop Flatten a Nested List Slice Lists Sort a Dictionary by Value Check If a List is Empty Concatenate Two Lists Check if a Key is Already Present in a Dictionary Split a List Into Evenly Sized Chunks Parse a String to a Float or Int Print Colored Text to the Terminal Convert String to Datetime Get the Last Element of the List Get a Substring of a String Randomly Select an Element From the List Check If a String Is a Number (Float)Count the Occurrence of an Item in a List Delete an Element From a Dictionary Create a Long Multiline String Convert Two Lists Into a Dictionary Trim Whitespace From a String Iterate Through Two Lists in Parallel Count the Number of Digits Present In a Number Check If Two Strings are Anagram Capitalize the First Character of a String Compute all the Permutation of the String Count the Number of Occurrence of a Character in String Remove Duplicate Element From a List

Files

Merge Mails Find the Size (Resolution) of an Image Find Hash of File Safely Create a Nested Directory Catch Multiple Exceptions in One Line Copy a File Python Program Read a File Line by Line Into a List Append to a File Extract Extension From the File Name Get the File Name From the File Path Get Line Count of a File Find All File with .txt Extension Present Inside a Directory Get File Creation and Modification Date Get the Full Path of the Current Working Directory Check the File Size

Python Program to Reverse a Number

To understand this example, you should have the knowledge of the following Python programming topics:

Example 1: Reverse a Number using a while loop


              
num = 1234
reversed_num = 0

while num != 0:
    digit = num % 10
    reversed_num = reversed_num * 10 + digit
    num //= 10

print("Reversed Number: " + str(reversed_num))

Output

In this program, while loop is used to reverse a number as given in the following steps:

First, the remainder of the num divided by 10 is stored in the variable digit. Now, the digit contains the last digit of num, i.e. 4. digit is then added to the variable reversed after multiplying it by 10. Multiplication by 10 adds a new place in the reversed number. One-th place multiplied by 10 gives you tenth place, tenth gives you hundredth, and so on. In this case, reversed_num contains 0 * 10 + 4 = 4. num is then divided by 10 so that now it only contains the first three digits: 123.
After second iteration, digit equals 3, reversed equals 4 * 10 + 3 = 43 and num = 12.
After third iteration, digit equals 2, reversed equals 43 * 10 + 2 = 432 and num = 1.
After fourth iteration, digit equals 1, reversed equals 432 * 10 + 1 = 4321 and num = 0.
Now num = 0, so the test expression num != 0 fails and while loop exits. reversed already contains the reversed number 4321.

Example 2: Using String slicing


              
num = 123456
print(str(num)[::-1])

Output

Using the string slicing concept, you can get reverse the string. ::-1 corresponds to start:stop:step. When you pass -1 as step, the start point goes to the end and stop at the front.

Also Read: