Why use 数年 in あれから１０数年?

Question

My question is on 「あれから１０数年」. My understanding is that this translates to roughly, "It's been 10 years since then."

The dictionary says「数年」 means "several years" or "a number of years". How does the meaning differ from「あれから１０年後」, and why would you use 「数年」when using a specific number?

Answer 1

あれから１０数年

It means 10 plus several years passed. like 14 to 17 years. 10 to 19 years passed. (corrected)

あれから１０年後

It means exactly 10 years later.

すう‐ねん【数年】

2、3か5、6ぐらいの年数。

source: デジタル大辞泉

じゅう‐すう〔ジフ‐〕【十数】

［語素］単位を表す語の上に付いたり、助数詞を伴ったりして、それが10以上20未満であることを表す。「―メートル」「―人」

source: デジタル大辞泉

Answer 2

It's less transparent in the example given, but there's a pretty good equivalent in similar expressions like: 二十数年 which in English would be, "20 some years"

Answer 3

数 in 十数 means that it is an unspecified number. That is, 十数 is 1X, where X is an unspecified digit. It is usually assumed that X is at least two and not too large; 19 would be probably too large to refer to as 十数.

This usage is not limited to 十数; the same usage can be seen in other unspecified numbers such as 数, 数十, 二十数, 三百数十, and so on. In most cases, using an unspecified number without a counter word would be incorrect or at least unnatural.

Although some people write 十数 as 10数, other people (including me) consider that the notation 10数 is wrong because recovering an actual digit (say, 3) in place of the letter 数 would make it something like 103, which is different from the intent.