How many cards are included in the game of Guesstimation? If you guessed 400 and your opponent guessed 430 - you'd technically both be wrong. Haha! But, the player who guessed 430 would actually be right because in Guesstimation, you don't have to know the exact answer, you just have to come closer than everyone else. The cards are organized into six categories: Dollars & Cents, What year was that?, No way!, Numbers in Nature, World records, Time traveler.