Tafsiran Yesaya 10:19: Rashi & Ibn Ezra

And the remaining trees of his forest The survivors of his armies.

And the rest of the trees, etc. There will escape but a few, whose number even a boy that has not yet had practice in counting, will be able to calculate and write down.

shall be few [lit. a number, i. e.,] easy to count, for they will be few, and a lad will be able to write them, and our Rabbis said that ten remained of them, for there is no small child who cannot write a small ‘yud.’