Weekly Puzzles
last updated 10/12/18

Click on any date for the solution.
Puzzles are pulled from various sources.  Credits are given in the solutions after the question has been posted a week.
2012-2013  ||  2013-2014 || 2014-2015 || 2015-2016 || 2016-2017 || 2017-2018 || 2018-2019
Puzzles - 2018-2019
We only know that the password of a safe consists of 7 different digits. The safe will open if we enter 7 different digits, and one of them matches the corresponding digit of the password. Can we open this safe in less than 7 attempts?
9/24 Adam and Eve play Rock, Paper, and Scissors ten times.  We know that
•    Adam uses three rocks, six scissors, and one paper.
•    Eve uses two rocks, four scissors, and four papers.
•    There are ties.
•    The order that Adam and Even play is not known.
Who wins and by how much?
You have a 3x3 inch square sheet of paper.  You want to cut out a pattern from the paper and use the pattern to completely cover a cube on all six sides without any overlap.  The pattern must be a single piece.  What is the largest cube you can cover?
The number 10 has four factors, 1,2,5, and 10.  Half of these factors are odd.

The number 21!=51,090,942,171,709,440,000 has a lot more than four factors.  :-)  If you pick a factor at random, what is the probability that it is odd.
You have a 1 meter stick.  You pick a random spot and break the stick at that point.  On average, what is the length of the short piece of the stick.
You have 1001 pennies in a row.  Some comes in and replaces every second penny with a nickel. Then someone replaces every third coin with a dime.  Then someone replaces every fourth coin with a quarter.  How much money will you have?
You have 100 pounds of a salt water solution which is 99 percent pure water (by weight).  You evaporate the solution until it is 98 percent pure water (by weight).  How many pounds of solution will you have?