Given a set $A$ of numbers and the number of desired subsets, $n$, how can I divide the numbers in set $A$ into $n$ subsets where each number in $A$ is used in one and only one subset and the sum of the numbers in each subset is optimally balanced?
If the subsets are named $S_1$ through $S_n$ then I would define the solution as the arrangement of the members of set $A$ that yielded the smallest value for
$$\max\left\{\sum S_1,\sum S_2,\ldots,\sum S_n\right\}-\min\left\{\sum S_1,\sum S_2,\ldots,\sum S_n\right\}\;.$$
As a practical matter, given that the size of set $A$ is small, a brute force solution is fine. I just need it to be accurate and reasonably straight forward to program.