Is the 了 in 你几岁了？ a change-of-state 了?

Question

There's a simple question we ask kids:

你几岁了？
_{How old are you?}

It's possible to ask it without the 了, i.e., 你几岁？. This makes me think this 了 is a change-of-state 了. It may just be a kind of "decorative" 了: something like 啦.

If this 了 is a change-of-state 了, then (to my understanding) this question can only be asked on the kid's birthday, as per this question.

Question: Is the 了 in 你几岁了？ a change-of-state 了?

Answer 1

It is indeed a change-of-state 了, more specifically, an "already" 了.

If this 了 is a change-of-state 了, then (to my understanding) this question can only be asked on the kid's birthday.

This isn't necessarily true, although on a kid's birthday you surely will ask the kid 你几岁了？instead of 你几岁呀？. The 了, in this particular scenario, does mean that the kid turns this age (the change of state) on this particular day.

But in other situations, 你几岁了？can still make sense. 刘月华(Liu Yuehua) et al.'s 《实用现代汉语语法》(Practical Modern Chinese Grammar) states that the 了 particle can be used to emphasise "时间、季节、年龄、数量的更迭变化" (the successive change of time, seasons, age or number). Therefore, there's a slight semantic difference between 你几岁了/你多大了/你多大年纪了？(with 了) and 你几岁呀？(without 了). It will be clearer if we observe the declarative form:

(A kid:)

我三岁，她五岁。I'm three, and she's five. (stating a fact)

我三岁了。 I've already turned three (this year). / I'm three (isn't it cool?!). (emphasising the passage of time)

(A middle-aged person:)

我今年五十五。 I'm fifty-five this year. (stating a fact)

我今年五十五了。I've turned fifty-five this year. (emphasising the passage of time)

我都五十五了，你还让我干这个？I'm already fifty-five, and you're making me do this? (if there's a 都 or 已经 in this sentence, omitting 了 won't sound natural to a Mandarin speaker's ears)

(An elderly:)

今年我九十八，明年就九十九了。 This year I'm ninety-eight, so the next year I'll turn ninety-nine. (in the first clause, this person's age, ninety-eight, is just a passing mention, a statement of fact; but in the second clause, they want to emphasise the fact that time flies and they'll be ninety-nine)

So, if you consider the following imaginary conversation:

(The reporter:) 您今年多大年纪了？ How old are you this year?

(The interviewee:) 一百一十七了。 Already 117 years old.

The reporter is asking How old are you already?, because 117 is a stunning age. This is emphasising the passage of time. Now, if it's not an reporter but a tired census taker who just cares about the facts, the question has a good chance to be presented as a mere 您今年多大年纪？

Or, consider a friend coming to a couple's house and cooing to their little kid, 你几岁了呀？ It will usually come with a tone of look at this little thing aww look how big you have become how many years have you been in this cruel world little darling or whatever people who like kids will think upon meeting a kid - it's about the change and passing of time, or to put it simply, a sense of already.

Answer 2

Yes, you can understand 了 in 你几岁了？ as a change-of-state 了, and it's a more natural way to ask for age than 你几岁？

Explanation: 你几岁了？ can be understood as aging is a process and this is asking which 'extend' has this process been for you, in this context, how old. And 你几岁？ would be simply asking for a property.

A bit similar to:

你几岁了？ -> How old have you become, over all these years?

你几岁？ -> How many ages are you, at this moment?

Answer 3

I don't think it's a change-of-state 了 in this case. Instead, 了 is for completion.

We understand 你几岁了 as 你已经几岁了 or 你已经长了几岁了. It's like saying how old have you reached/become.

PS. 你几岁 also works in practice.