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Best Guess · Puzzle #40 · Sunday, November 8

Best Guess: the answers

Four questions, each with one true number. Here they are with their answers, how to reason each one out, and where the number comes from. Play today's Best Guess.

  1. 1. How many retail post offices did the US Postal Service operate in fiscal 2025?

    The answer: 30,972. That is more locations than McDonald's and Starbucks have in the US combined.

    Napkin math
    1. 330Mpeople in the US
    2. ÷15kpeople to a post office

    ≈22kretail offices

    The real answer is 30,972 retail offices (United States Postal Service). On a napkin, take 330 million people in the US, divided by 15,000 people to a post office, and you get about 22,000 retail offices. That comes out 1.4 times too low, and a guess that far off still scores 8.5 out of 10. Any guess from 15,000 retail offices to 62,000 retail offices scores 7.0 or better, because the game only counts how many times off you are.

    Source: United States Postal Service, Postal Facts - Size and Scope

  2. 2. How many pounds of Moon rock, soil and dust did the six Apollo landings bring back to Earth, in total?

    The answer: 842 pounds. The haul came as about 2,200 separate samples from six different landing sites.

    Napkin math
    1. 6landings on the Moon
    2. ×100pounds brought home from each

    ≈600pounds

    The real answer is 842 pounds (NASA Johnson Space Center, Astromaterials Curation). On a napkin, take 6 landings on the Moon, times 100 pounds brought home from each, and you get about 600 pounds. It's 1.4 times too low, which as a guess would still have scored 8.5 out of 10. Because only the ratio counts, anything between 420 pounds and 1,700 pounds was worth 7.0 or more.

    Source: NASA Johnson Space Center, Astromaterials Curation, Lunar Rocks and Soils from Apollo Missions

  3. 3. How many servings of Coca-Cola Company drinks are consumed worldwide every day?

    The answer: 2.2 billion. That is 2.2 billion of an estimated 65 billion servings of all beverages consumed worldwide each day.

    Napkin math
    1. 8Bpeople on Earth
    2. ÷4people for each Coke-brand drink a day

    ≈2Bservings

    The real answer is 2.2 billion servings (The Coca-Cola Company, as of 2025). To reason it out, take 8 billion people on Earth, divided by 4 people for each Coke-brand drink a day, and you get about 2 billion servings. It's 1.1 times too low, which as a guess would still have scored 9.6 out of 10. Any guess from 1.1 billion servings to 4.4 billion servings scores 7.0 or better, because the game only counts how many times off you are.

    Source: The Coca-Cola Company, Form 10-K for fiscal year 2025

  4. 4. How many gallons of water does a wild Asian elephant drink in a day?

    The answer: about 50 gallons. Its trunk can hold about 2 gallons at a time, and it also eats 165 to 330 pounds of food a day.

    Napkin math
    1. 12kpounds an elephant
    2. ÷150pounds a person
    3. ×0.5gallons a person drinks a day

    ≈40gallons

    The real answer is about 50 gallons (Smithsonian's National Zoo & Conservation Biology Institute). Without looking anything up, take 12,000 pounds an elephant, divided by 150 pounds a person, times 0.5 gallons a person drinks a day, and you get about 40 gallons. The estimate is 1.3 times too low, close enough to score 9.0 out of 10. Any guess from 25 gallons to 100 gallons scores 7.0 or better, because the game only counts how many times off you are.

    Source: Smithsonian's National Zoo & Conservation Biology Institute, Asian elephant

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