Find the Missing Number

Create a function that takes an array of numbers between 1 and 10 (excluding one number) and returns the missing number.

Examples

missingNum([1, 2, 3, 4, 6, 7, 8, 9, 10]) ➞ 5

missingNum([7, 2, 3, 6, 5, 9, 1, 4, 8]) ➞ 10

missingNum([10, 5, 1, 2, 4, 6, 8, 3, 9]) ➞ 7

Notes

• The array of numbers will be unsorted (not in order).
• Only one number will be missing.