Omitting を in 十数えました


I came across the sentence その子は指で十数えました in writing, and I was under the
impression that, in written Japanese particles are not omitted. I can see that
that sentence means, "That child counted to ten with her fingers". However,
I'm having difficulty understanding if there should be an を (or another
particle) after 十. I feel like 十 should be the direct object of 数えました, but
maybe my understanding of the verb 数えました is incorrect.




No particle is omitted in this sentence. We rarely say 十を数える regardless of
it's written or spoken, in the first place. This 十 is like an adverb that
directly modify a verb without any particle, and [this happens very
often](https://japanese.stackexchange.com/q/17816/5010).

By the way, this 十 can be read as じゅう and とお, both of which are fine but the
former is common.

Here are some formal ways to use 数える:

>   1. 五【ご】数える count five (aloud / with a finger)
>   2. 五【いつ】つ数える count five (aloud / with a finger)
>   3. ボールの数を数える count the number of balls
>   4. ボールを数える count the balls
>

You can omit を in the last two examples in casual conversations.




No particle is omitted in this sentence. We rarely say 十を数える regardless of
it's written or spoken, in the first place. This 十 is like an adverb that
directly modify a verb without any particle, and [this happens very
often](https://japanese.stackexchange.com/q/17816/5010).

By the way, this 十 can be read as じゅう and とお, both of which are fine but the
former is common.

Here are some formal ways to use 数える:

>   1. 五【ご】数える count five (aloud / with a finger)
>   2. 五【いつ】つ数える count five (aloud / with a finger)
>   3. ボールの数を数える count the number of balls
>   4. ボールを数える count the balls
>

You can omit を in the last two examples in casual conversations.

