Hello from Florida, USA. Please help: how do you properly write out the year on invitations and formal bulletins for weddings or any special occasion? Is it

1. Two Thousand Six


2. Two Thousand and Six

I feel comfortable with #1 because it follows the format of properly writing a check; but, have seen #2 so many times, especially from printers who create wedding invitations.

Thank you.
There is no single proper way. Either of the ones you suggest are fine.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Thank you, Mister Micawber. Taking this one step further, which choice do you prefer? Have you seen invitations or the like written with both choices?

Just curious.
If I had to handwrite hundreds of the things, I would certainly choose the first. Otherwise, I suppose the second is more elegant (more words = increased formality is a very general rule of English).