It is a stupid quiz, 30% of the questions deal with numbers only someone involved with pizza statistics in the US would even have a guess about.
The quiz was for viewers who had already watched the show to see what they remembered.
Even so, for the slices/second question I guessed based on an assumption of 50k pizzerias X 80 pies/day. Even if I had missed that one, I still would have found out that the answer was 350 and used that figure to calculate the subsequent questions.
For the around the world question, I calculated 55, picked 52 and then the correct answer on the second try. I think I underestimated the impact of those tiny delivery pies.
For the cheese/year question I came up with 689 million lbs based on 8 oz/16" pie. I guessed 1B and then 2B. There must be some cheesy pizzas out there.