> For the complete documentation index, see [llms.txt](https://gl01.gitbook.io/gfg-editorials/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gl01.gitbook.io/gfg-editorials/2024/02-2024-feb-25/28-check-if-a-number-is-divisible-by-8.md).

# 28. Check if a number is divisible by 8

The problem can be found at the following link: [Question Link](https://www.geeksforgeeks.org/problems/check-if-a-number-is-divisible-by-83957/1)

## My Approach

After analyzing the pattern, we've observed that if the last three digits of a number are divisible by 8, then the entire number is also divisible by 8. Therefore, let's solve this question using that approach.

* I extract the last three digits of the given string.
* I convert these last three digits to an integer.
* I check if this integer is divisible by 8.
* If it is divisible by 8, I return 1; otherwise, I return -1.

## Time and Auxiliary Space Complexity

* **Time Complexity**: O(1), as the operations are constant time operations.
* **Auxiliary Space Complexity**: O(1), as no extra space is used other than a few variables.

## Code (C++)

```cpp
class Solution {
public:
    int DivisibleByEight(string s) {
        int n = s.size();
        int l = stoi(s.substr(max(n - 3, 0)));
        return l % 8 == 0 ? 1 : -1;
    }
};
```

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