וּשְׁאָ֥ר עֵ֛ץ יַעְר֖וֹ מִסְפָּ֣ר יִֽהְי֑וּ וְנַ֖עַר יִכְתְּבֵֽם׃ (פ)
And the remnant of the trees of his forest shall be few, That a child may write them down.
Rashi on Isaiah
And the remaining trees of his forest The survivors of his armies.
Ibn Ezra on Isaiah
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.
Rashi on Isaiah
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.’