我27 我27岁 我今年27岁 我今年周岁26，虚岁27 我88年 我1988年出生 我属龙，我88年出生。 中国人基本就这几种说法

It really depends on whom You're asking. It varies from the kids to the old.

我 <number> 岁。

我今年20岁。I am twenty years old this year. It's free to indicate your age or something,but it is better to adjust your words to show your respect when you ask for someone else's information.

我(I)今年（this year）21岁（21 years old）