**Problem Statement:** Given a decimal number, convert it into Octal Number.

**Examples:**

Example 1:Input:17Output:21Explanation:Octal Equivalent of 17 is 21Example 2:Input:45Output:55Explanation:Octal Equivalent of 45 is 55

**Solution**

** Disclaimer**:

*Don’t jump directly to the solution, try it out yourself first.*

**Approach**:

For Decimal to Octal Conversion, we will divide the given number by 8 ( Since Octal Numbers System has 8 digits in use ) repeatedly, and its remainder will be stored till the number becomes zero.

Let us take an example for 136

**Step 1**: Divide 136 by 8, the remainder will be 0 and now n becomes 17.

**Step 2**: Now divide 17 by 8, the remainder will be 1 so our ans till now becomes 10 and n becomes 2

**Step 3**: Divide 2 by 8, the remainder will be 2, so the answer till now becomes 210 and n becomes 0

**Step 4**: since n becomes 0, so print the answer i.e. 210 which is the octal equivalent of the decimal.

**Code:**

## C++ Code

```
#include <iostream>
#include <math.h>
using namespace std;
int DecimaltoOctal(int decimal)
{
int Octal = 0;
int i = 0;
while (decimal != 0)
{
int rem = decimal % 8;
Octal += rem * pow(10, i);
i++;
decimal = decimal / 8;
}
return Octal;
}
int main()
{
int decimal = 136;
cout <<"The Octal conversion of the given decimal number is "<<DecimaltoOctal(decimal) << endl;
return 0;
}
```

**Output:**

The Octal conversion of the given decimal number is 210

**Time Complexity: **O(log n) where n is the number

**Space Complexity: **O(1)

## Java Code

```
import java.util.*;
public class Main {
public static int DecimaltoOctal(int Decimal) {
int i = 0;
int Octal = 0;
while (Decimal != 0) {
int rem = Decimal % 8;
Octal += rem * Math.pow(10, i);
i++;
Decimal /= 8;
}
return Octal;
}
public static void main(String[] args) {
int Decimal = 136;
System.out.println("The Octal conversion of the given decimal number is
"+DecimaltoOctal(Decimal));
}
}
```

**Output:**

The Octal conversion of the given decimal number is 210

**Time Complexity: **O(log n) where n is the number

**Space Complexity: **O(1)

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