You'll see an item, the year, and where it was sold.
Type what you think it cost back then. Guess the sticker price people actually paid that year, not today's money.
Lock in your price to see the real one and the story behind it.
Five items a day. Your receipt shows your total out of 500.
Scoring
Each item is worth up to 100 points. Points depend on how far off you are in percent, so being $1 off on a candy bar costs you more than being $1 off on a car.
Some items ask a different question. What year was it? gives you the price and you guess the year: within two years is a bullseye, and 25 or more years off scores nothing. How many could it buy? gives you an amount of money and you guess how many you could take home. For the really big prices you can type shorthand like 15m or 1.6b.