There are many possibilites for this effect using partnered code.

Here is something I have been experimenting with. The principle is pretty old but, and I will admit this readily, Banachek's use of it sucked me in until, oh, about 3 words into the explanation (which shows both the power of the trick and the excellence of Banachek's instructions). In his video series, Banachek has a divination of a serial number on a piece of currency. Prior to that, he figures out which envelope the bill is in even though his back is turned and the spectator moves the envelopes around. Those of you know what I am talking about....well, you know what I am talking about.

The point is, you can use it for anything where locations of objects are switched and it doesn't have to be a specific number of objects (as long as you understand the principle involved). The one drawback in copying exactly what Banachek does (besides the fact that you should make a routine your own) is that you need to know where the object is initially. Now, there are numerous ways to get around this and I am sure you can figure this out for yourself, but this is also a wonderful, do it anytime, tool to have in your bag (or not in your bag, lol).

-Carlos