function largestNumber(num) {
return num.sort(function(a, b) {
return (b + '' + a )  (a + '' + b);
}).join('').replace(/^0*/,'')  '0';
}
5 lines solution in JavaScript

Hi @brianho1023,
sorry for the late reply, the inner function does below:
 it sorts (num.sort) all the numbers with a given sorter (function (a, b))
 it concatenates (.join) all sorted numbers
 it removes leading extra '0' if any (replace)
 if the concatenated string is empty, return '0' instead
And the sorter is quite simple: compare by a concatenated b with b concatenated a, for example if a is 3 and b is 4, then we compare 34 with 43.