CU. Eminently Logical Pirates
Pirates are well known for their logical and rational behavior. How should they divide up some loot?
Archive for August, 2007
CT. Odd People
This week we consider an odd number of odd people are milling about
with water pistols, on a large flat field. At a signal, everyone turns and squirts the closest
person (We may assume, since they are just milling about randomly, there is
a unique closest person to squirt.) Show that there will always be at least
person left dry!
Last week’s puzzle on Perfectly Summing Sets can be solved in many different ways; here’s one!
Follow-up: Weird sums
What numbers can 1,2,4,8,16,… etc “form”? Well, every number can be “formed” by summing various powers of 2. For example, 13 = 1 + 4 + 8.
In this way, we could say that a power of 2, say 64, is “full of divisors” since it has enough divisors to form any number up to 64. Its divisors are of course 1, 2, 4, 8, 16 and 32, and we can form any number from 1 to 63 by summing up these divisors as needed.
But what other numbers of “full of divisors”?
CS. Perfect Sums
First, let’s answer last week’s puzzle on clocks!
As it turns out, there are 143 times in each twelve hour period for which you can switch the hands of a clock and still have a legitimate time! It’s easy to find these by plotting the positions of the hands throughout the day:
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