How many n in a factorial?

I am unable to understand this flash card from group 2 quant. is anyone there to explain this? Thank you!

See the “# of Numbers in Factorials” video on PrepSwift.

Bumping this question - I don’t understand the flashcard and I am not following prepswift / have an account with them. I am following Greg’s videos.

Explain the issue you’re having with the concept, in detail.