Author Archives: Kurt von Laven

There are nine coins, one slightly heavier than the rest.  You have three old-fashioned balances like these that you can use to compare the weights of whichever sets of coins you would like. Exactly one of the balances provides arbitrary readings (neither necessarily right nor necessarily wrong), but you don’t know which balance lies. Find [...]

There are eight coins, one of which weighs a slightly different amount from the rest.  You have an old-fashioned balance like this one that you can use to compare the weights of whichever sets of coins you would like.  Find the special coin in only three weighings.  Bonus points if you can also determine whether the [...]

Greg says, “I’ll tell Phil the product of two integers, each of which is greater than one, and Sean their sum.” After Greg whispers to both of them, Phil shrugs, “I don’t know Greg’s numbers.” “I already knew that,” Sean states. “But now I do!” Phil exclaims. Sean smirks, “Well then so do I.” What might Greg’s [...]

There is a line of Cylons and humans with more Cylons than humans.  Each creature whispers to you the number of Cylons in front of them.  Cylons can distinguish Cylons from humans, but humans can not, so they simply provide a reasonable guess.  Find a Cylon.

You are given a ball composed entirely of gold and another made only of silver. Both are painted with an identical layer of impenetrable, irremovable white paint. Both share the same mass and volume. Distinguish them without damaging them.

After the positive attention our last puzzle received, we’ve decided to share more.  If you’d ever like to see all the puzzles at once, they’ll both be tagged with and categorized under “Puzzles.” Can you help the dog face left by only moving two “toothpicks”? We only know one answer to this question (at least so [...]