～の時 vs ～歳の時: What's the difference?


When referring to a time where one was a certain age, are there any
differences in meaning, nuance or usage between saying, for example, `18の時`
and `18歳の時`.

I always thought you needed to have the `歳`, but I ran into an example of it
without it, so now I'm wondering.

Bonus question: Is this different for `はたち`? I.e. can you say `20の時`?




The nuances are pretty much aligned with the English equivalents

> When I was 18, ...
>
> When I was 18 years old, ...

Appending 歳 is more complete and would be favoured in formal situations (e.g.
as part of 丁寧語).

Bonus question: `20のとき` sounds childish (albeit you being clearly over 20),
like [5日]{ごにち} instead of いつか, so はたちの時 escapes the simplification rule and
would be preferred in both formal and informal contexts.




The nuances are pretty much aligned with the English equivalents

> When I was 18, ...
>
> When I was 18 years old, ...

Appending 歳 is more complete and would be favoured in formal situations (e.g.
as part of 丁寧語).

Bonus question: `20のとき` sounds childish (albeit you being clearly over 20),
like [5日]{ごにち} instead of いつか, so はたちの時 escapes the simplification rule and
would be preferred in both formal and informal contexts.

