〜ことか koto ka
〜ことか（koto ka）means “how ...! (exclamation of degree)”. An emphatic exclamation expressing a strong feeling about a great degree—how much, how long, how happy, etc. Formation: 普通形＋ことか（多与 どんなに／なんと／どれほど 等呼应）
how ...! (exclamation of degree)
N2Formation
普通形＋ことか（多与 どんなに／なんと／どれほど 等呼应）
Explanation
An emphatic exclamation expressing a strong feeling about a great degree—how much, how long, how happy, etc. Usually paired with どんなに, なんと, or どれほど. 〜ことだろう is a softer variant.
Examples
Note
Literary and emotional; the question form is rhetorical, not a real question. 〜ことだろう softens the same feeling.
FAQ
〜ことか — what does it mean and how is it used?
how ...! (exclamation of degree). An emphatic exclamation expressing a strong feeling about a great degree—how much, how long, how happy, etc. Usually paired with どんなに, なんと, or どれほど. 〜ことだろう is a softer variant.
〜ことか — how do you form it?
普通形＋ことか（多与 どんなに／なんと／どれほど 等呼应）
〜ことか — any usage notes?
Literary and emotional; the question form is rhetorical, not a real question. 〜ことだろう softens the same feeling.