Finding a number that repeats even no of times where all the other numbers repeat odd no of times

Question

Given is an array of integers. Each number in the array repeats an ODD number of times, but only 1 number is repeated for an EVEN number of times. Find that number.

Answer 1

I don't know what the intended meaning of "repeat" is, but if there is an even number of occurrences of (all-1) numbers, and an odd number of occurances for only one number, then XOR should do the trick.