Your question is of mathematics nature – combinations and permutations. You are actually asking the number of possible permutation for string length 7.

The formula is factorial(numOfchar).

`In this case 7! = 7x6x5x4x3x2x1 = 5040.`

```
public static void main(String[] args) {
String str = "ABCDEFH";
System.out.println("Number of permutations for " + str + " is : " + factorial(str.length()));
}
public static int factorial(int n)
{
if (n == 0)
return 1;
int result = factorial(n-1)*n;
return result;
}
```

**Program Output:**

`Number of permutations for ABCDEFH is : 5040`

Since you tagged `Java`

, this is one way you can get the it done with Java.