You and a friend have a pile of 15 pennies and decide to play a little game. You will each take turns removing pennies from the pile. On each turn you or your friend can take 1, 2, or 3 pennies. The loser is the person who takes the last penny. You are allowed to go first. How many pennies should you take?
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.