10 Year or 10th Year Anniversary?

[melina74]

Hello all!
I'm hoping that somebody out there can help with this question.

For a poster celebrating the anniversary of a company's ten years?
Is it better to say
10th Year Anniversary or
10 Year Anniversary?

And would the answer change if the word 'celebration' followed it?
10th year anniversary celebration
or
10 year anniversary celebration?

I cannot seem to find a grammar rule that applies to this!

Can anyone help?

Thanks, in advance!

[Ouisch]

10 Year Anniversary

or

10th Anniversary Celebration

or you could say

Celebrating our 10th year in business

[melina74]

Thank you, Ouisch!

Is there a rule associated with the advice you've given me?
Just so I can make some sense of it?