For the use of ninety and ninetieth see the examples at five and fifth
Article in commemoration of the ninetieth birthday of Dr. Sun Yat-sen.
關於ninety和ninetieth的用法見five和fifth詞條中的示例
The present Protocol shall enter into force for the States whichhave ratified, accepted, a pproved or acceded to it on the ninetieth dayfollowing the date on which the following requirement s are fulfilled;
And next month's sixteenth is the ninetieth birthday of the old emperor of the Oriental family. Please give him a treat anyway.