What is the correct result?

[KeithB]

The obvious answer is to use RPN.

I think I have quoted it before, but here is APL's entry in "The Devil's DP Dictionary":

APL n, [A Personal Language, A Packed Language, or rarely A Programming Language]
A language devised by K Iverson, so compacted that the source code can be freely disseminated without revealing the programmer's intentions or jeopardizing proprietary rights.

There are three things a man must do
Before his life is done
Write two lines in APL
and make the buggers run.