**Reverse number program in java** is simple program which takes the number input and reverse that number.

Lets see how to reverse number in java.

**Reverse Number Logic**

We separate digits in number by modulus operation which gives us a digit in a number.

**Rem = number % 10**

After separating number we store that digit in another variable with considering its unit places which we perform as

**Reverse = Reverse × 10 + Remember**

We repeated step 1 and 2 till number ends.

**Reverse Number Example**

Number = 342

Reverse number = 243

## Reverse a Number in java

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import java.util.*; public class Main { public static void main(String[] args) { int temporary ,n,rev=0,x; Scanner sc= new Scanner(System.in); System.out.println("Enter a number"); n=sc.nextInt(); temporary =n; while(n>0) { x=n%10; rev=rev*10+x; n=n/10; } System.out.println("The reverse of "+temporary+" is "+rev); } } |

**Output :**

**Explanation :-**

**1. Here we did initialization for**

temporary ->To store the entered value(i.e ‘n’) as you will come to know at the end of the program

n->To store number given by a user.

rev->To store the reverse of a number.It is initialized to zero

x->To store n%10.

**2. First of all, we got a number ‘n’ from a user and then stored it in a temporary variable called as ‘temporary ‘ for restoring the value.(remember this point).**

**3. Now the main logic comes here**

let the number ‘n’ be 321 and as 321>0, while loop gets executed

then x=321%10—>which is 1.

rev=0*10+1——–>1

n=321/10———>32

The rev for the first loop execution is rev=1.

**4. Now the number ‘n’ has become ’32’ and n>0, while loop executes for the 2nd time.**

then x=32%10—>which is 2.

rev=1*10+2——–>12

n=32/10———>3

The rev when loop executed the second time is rev=12.

**5. Now the number ‘n’ has become ‘3’ and n>0, while loop executes for the 3rd time**

then x=3%10—>which is 3.

rev=12*10+3——–>123

n=3/10———>0

The rev when loop executed the third time is rev=123.

**6. Now as the number of variable ‘n’ is 0 which is not n>0 then the loop terminates.Then the final reverse is ‘123’.**

**7. So now I hope you understood why the temporary variable is used.It is because the value in ‘n’ becomes 0 at the end of the program so for restoring this value to print at the end we used ‘temporary ‘(as from the 2nd point).**

**8. Finally, it prints the value in ‘rev’.**

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