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.
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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).