Which cylinder is cylinder #5?

I posted this the other day but in a hurry with not much detail so here it is again I drive a 2004 Ford taurus with a v6 24v DOHC Duartec engine and my computer is reading a bad ignition coil on (coil e #5) replacing it won't. Be difficult I'm just not sure how to determine which cylinder is which

The cylinders are numbered 123 on the bank closest to the radiator. 456 are on the rear bank. #5 is a middle cylinder. As you stand looking at the belts 456 are on your right. 1 & 4 are closest to the belt

Have you tested that coil?

It would be the one in sequence between 4 and 6.