# C++ Program for Largest K digit number divisible by X

Integers X and K are given. The task is to find highest K-digit number divisible by X.

Examples:

```Input : X = 30, K = 3
Output : 990
990 is the largest three digit
number divisible by 30.

Input : X = 7, K = 2
Output : 98
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

An efficient solution is to use below formula.

```ans = MAX - (MAX % X)
where MAX is the largest K digit
number which is  999...K-times```

The formula works on simple school method division. We remove remainder to get the largest divisible number.

 `// CPP code to find highest K-digit number divisible by X ` `#include ` `using` `namespace` `std; ` ` `  `// Function to compute the result ` `int` `answer(``int` `X, ``int` `K) ` `{ ` `    ``// Computing MAX ` `    ``int` `MAX = ``pow``(10, K) - 1; ` ` `  `    ``// returning ans ` `    ``return` `(MAX - (MAX % X)); ` `} ` ` `  `// Driver ` `int` `main() ` `{ ` `    ``// Number whose divisible is to be found ` `    ``int` `X = 30; ` ` `  `    ``// Max K-digit divisible is to be found ` `    ``int` `K = 3; ` ` `  `    ``cout << answer(X, K); ` `} `

Output:

```990
```

Please refer complete article on Largest K digit number divisible by X for more details!

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