This question is a classic trick that depends on how you interpret the text. Let’s take a closer look:

In the text of the question: If you look for digits, you won’t see any (all numbers are spelled out).

Logically speaking: We see two “numbers” (or words that indicate quantity): “How many?” (an interrogative word) and “one” (hidden in the root of the word “numbers” – plural). However, if you ask about specific, spelled out values, there is only one (or zero digits).

Visually speaking: If you read this text on a screen with a digital font, some people may see hidden shapes in the letters (e.g. the zero in the letter “O”), but that is already a high level of abstraction.

So my answer is this: I don’t see any numbers (0, 1, 2…) in the notation of your question, but I do see a word that asks about quantity (“how much”) and a word that describes the concept itself (“numbers”).

Did I understand you correctly, or was that some kind of visual joke?