grammar - Different ways to say several

何本か重要な電話をかけ、...
He made several important phone calls and ...

As I puzzled about why phone calls might use the counter 本 (see this question) I wondered more generally about how to say several.

Is there a difference between "何 + counter + か" and "数 + counter"?

If you don't know what counter to use can you always just use いくつか instead?

I think I may be getting mixed up about which ones are used adjectively and which ones are used adverbially, or if they can be used both ways.

Answer

何本{なんぼん}か重要{じゅうよう}な電話{でんわ}をかけ、...

He made several important phone calls and ...

The most important thing first.

While the English translation above is a valid one, it is grammatically structured differently from the Japanese original.

In the original, 「何本か」 functions adverbially to modify the verb 「かけ」. In other words, it does not function adjectivally to modify the noun 「電話」. This is why while "several important phone calls" is a perfectly independent and meaningful noun phrase, 「何本か重要な電話」 is not because the 「何本か」 is left hanging without a verb to modify. Only by changing 「何本か」 to 「何本かの」, it can function adjectivally like "several" can in English.

Since 「何本か」 functions adverbially, you can naturally position it directly in front of the verb 「かけ」 and say 「重要な電話を何本かかけ」.

Is there a difference between "何 + counter + か" and "数 + counter"?

There is no difference in the sense that both function adverbially. Just like with the former, you need to add a 「の」 to the latter to make it function adjectivally. This is a grammar point on which many J-learners make mistakes.

It is incorrect to say:

「数個みかん」、「数匹犬」、「何枚かピザ」、「何人か日本人」, etc.

It is only correct to say:

「数個のみかん」、「数匹の犬」、「何枚かのピザ」、「何人かの日本人」, etc.

Very common mistakes also include:

「ふたつメロンパン」、「みっつリンゴ」, etc. Got to insert a 「の」 into those.

If you don't know what counter to use can you always just use いくつか instead?

For only inanimate objects, yes. It will make you sound childish, but what can you do if you do not know the right counter?

If, however, you used 「いくつか」 to count animate objects (especially humans), you would sound more than childish, so please do not forget the counter 「人{にん}」 and if all possible, 「名{めい}」 as well.

EXCEPTIONS:

Proper nouns such as 「六本木{ろっぽんぎ}」、「九十九里浜{くじゅうくりはま}」, etc. Inserting a 「の」 is a no-no. No pun intended.