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
10 year anniversary celebration?

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

Can anyone help?

Thanks, in advance!