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Price tags · Puzzle #13 · Monday, October 12

Price tags: 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 Price tags.

  1. 1. A year of public school per student: How much did US public school systems spend per pupil on current operations in fiscal year 2024?

    Photo: Frances Benjamin Johnston (1864-1952), photographer, Public domain
    Measured by
    US Census Bureau, Annual Survey of School System Finances
    Students counted
    About 46.4 million
    Salaries and wages per pupil
    About $9,685

    The answer: about $17,600. Salaries and employee benefits make up most of each pupil's share.

    Napkin math
    1. 180days in a school year
    2. ×$100a day for each student

    ≈$18k

    Source: US Census Bureau, Public Elementary-Secondary Education Finances: Fiscal Year 2024, Summary Table 14 (Per Pupil Amounts)

  2. 2. Black Friday online: How much did American shoppers spend online on Black Friday 2025?

    Day
    Friday, November 28, 2025
    Counts
    Online spending at US retail websites

    The answer: about $11.8 billion. It was a record, according to Adobe Analytics, which tracks more than 1 trillion visits to US retail websites.

    Napkin math
    1. 100Mshoppers buying online that day
    2. ×$100each

    ≈$10B

    Source: TechCrunch, Black Friday sets online spending record of $11.8B, Adobe says

  3. 3. Marilyn Monroe's 'Happy Birthday, Mr. President' dress: What did Marilyn Monroe's 'Happy Birthday, Mr. President' dress sell for at Julien's Auctions in Los Angeles in November 2016?

    Photo: Frank Powolny, Public domain
    What
    The custom-made Jean Louis gown from Marilyn Monroe's 'Happy birthday, Mr President' performance
    Buyer
    Ripley's Believe It or Not!
    Sold
    Julien's Auctions, Los Angeles, 2016

    The answer: $4.81 million. Guinness World Records lists it as the most expensive dress ever sold at auction.

    Napkin math: Famous film costumes go for hundreds of thousands to a few million; this is perhaps the most famous dress in pop culture.

    Source: Guinness World Records, Most expensive dress sold at auction

  4. 4. An Olympic pool of milk: At the US average store price of whole milk in August 2026, what would it cost to fill an Olympic swimming pool with milk?

    Photo: Cabrils, CC BY-SA 4.0
    Pool
    50 by 25 meters, 2 meters deep
    Holds
    about 660,000 gallons

    The answer: about $2.8 million. That's about 660,000 gallon jugs, each at the Bureau of Labor Statistics' city average price.

    Napkin math
    1. 660kgallons in the pool
    2. ×$4a gallon of milk

    ≈$2.64M

    Source: Federal Reserve Bank of St. Louis (FRED), from the US Bureau of Labor Statistics, Average Price: Milk, Fresh, Whole, Fortified (Cost per Gallon/3.8 Liters) in U.S. City Average

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