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.
Main.javaRun in Compiler →
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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