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Reverse a Number in Java

Java program to reverse a number using while loop.

Last updated: 11 January 2026

Method 1: Using While Loop

Extract digits and build reversed number.

public class ReverseNumber {
    public static void main(String[] args) {
        int num = 1234, reversed = 0;
        
        System.out.println("Original Number: " + num);

        while(num != 0) {
            int digit = num % 10;
            reversed = reversed * 10 + digit;
            num /= 10;
        }

        System.out.println("Reversed Number: " + reversed);
    }
}
Output:
Original Number: 1234
Reversed Number: 4321

Explanation

Modulus 10 gets the last digit. Multiply current result by 10 and add new digit.

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