You have a row of 1,000 coins, all of which are heads up. You flip the second, fourth, sixth, and all other even coins over so that they’re tails. Then you flip over the third, sixth, and all other coins which are multiples of three. Now you do this for every fourth coin, every fifth coin, etcetera, all the way up to every thousandth coin. Which coins are heads up, and why?
I heard this puzzle mentioned on TV the other day on Growing Pains of a Teenage Genius, and decided to solve it with Excel.
This spreadsheet lets you change the number of coins, or even change the number of sides of the object (a coin is a two sided object, but you could change it to a six sided dice for example).
#growingpainsofateenagegenius #excel #puzzle #logic