# How can I find the missing number in an array with an integer between 1 and 100?

Here's what I did. What can I do next? Can anyone suggest? I am looking for a bitt solution.

``````public static void main(String args[]) {

// one missing number
printMissingNumber(new int[]{1, 2, 3, 4, 6}, 6);

// two missing number
printMissingNumber(new int[]{1, 2, 3, 4, 6, 7, 9, 8, 10}, 10);

// three missing number
printMissingNumber(new int[]{1, 2, 3, 4, 6, 9, 8}, 10);

// four missing number
printMissingNumber(new int[]{1, 2, 3, 4, 9, 8}, 10);

// Only one missing number in array
int[] iArray = new int[]{1, 2, 3, 5};
int missing = getMissingNumber(iArray, 5);
System.out.printf("Missing number in array %s is %d %n",
Arrays.toString(iArray), missing);
```

```

}

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For n consecutive numbers, the sum s = n (n + 1) / 2.

Sum the numbers in the array and subtract them from s to find the missing number.

+2

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If `n`

is the largest number, and only one is missing, then the missing number

``````n * (n + 1) / 2 - sum{elements in your array}
```

```

The first term is the sum of `n`

consecutive integers from 1 to including `n`

.

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