A riddle problem is a question or statement intentionally phrased so as to require ingenuity in ascertaining its answer or meaning, typically presented as a game.  Below is a list of the past problem of the week riddles in descending chronological order.

Riddle: When can you add two to eleven and get one as the correct answer?
Answer: When you add two hours to eleven o'clock, you get one o'clock.
Riddle: If you have two coins which total 35 cents and one of the coins is not a dime, what are the two coins?
Answer: A quarter and a dime. One coin is not a dime, but the other one is.
Riddle: Three playing cards in a row. Can you name them with these clues? There is a two to the right of a king. A diamond will be found to the left of a spade. An ace is to the left of a heart. A heart is to the left of a spade. Now, identify all three cards.
Riddle: A car's odometer shows 72927 miles, a palindromic number. What are the minimum miles you would need to travel to form another?
Riddle: An item is made from lead blanks in a lathe shop. Each blank suffices for 1 item. Lead shavings accumulated for making 6 items can be melted and made into a blank. How many items can be made from 36 blanks?
Answer: From 36 blanks there are 36 items made. The lead shavings are enough to make 6 blanks. Which make 6 more items. But don't stop here. The new shavings are good for 1 more item. Total: 43.
Riddle: While on my way to St. Ives, I saw a man with 7 wives. Each wife had 7 sacks. Each sack had 7 cats. Each cat had 7 kittens. Kitten, cats, sacks, wives, How many were going to St. Ives?