[curriculum]

Along the same lines, asking

> How many words are in the sentence "This is a test of artificial intelligence"?

yields an answer of:

> There are 8 words in the sentence "This is a test of artificial intelligence."

(There are 7).

[coderoffortune]

My guess is that AI omitted 'a' because this is essentially how natural language processing works. Perhaps it cannot see 'a' because the input has been stripped of 'a' or 'the', and so on.