Logic Puzzles to Keep Your Mind Sharp

By American Geriatrics Society (AGS), Health in Aging Foundation

Put on your thinking cap to solve these logic puzzles! Each has just one answer. Levels are Easy, Tricky, Tough, and Treacherous, “Easy” being (of course) the easiest puzzles, and “Treacherous” being the most difficult ones.

  1. Easy: How many times can a mathematician subtract ten from 100?
  2. Easy: Decipher this clue: YYYMEN
  3. Tricky: A woman gave birth to two boys on the same day, in the same year, within minutes of each other, yet they were not twins. How is this possible?
  4. Tricky: Add one line, and one line only, to make the following statement correct: 5 + 5 + 5 = 550
  5. Tricky: Alexander is a great magician, skilled in many things. He weighs exactly 199 pounds and is about to cross a bridge with a strict weight limit of 200 pounds.

    The problem is he is carrying three pieces of gold, each weighing 8 ounces each. The gold puts him 8 ounces over the strict weight limit. What does Alexander do to cross the bridge safely with all three pieces of gold?

  6. Tough: Two people stand on opposite corners of a handkerchief. They do not stretch or alter the handkerchief in any possible way.

    How can they both stand on the handkerchief simultaneously without having any possibility whatsoever of touching each other?

  7. Tough: Under what circumstance could a person walk along a railroad track, discover an oncoming train, and have to run toward the train to avoid being struck?
  8. Tough: Imagine this scenario. You have an extremely valuable item you need to send in the mail to an acquaintance. You have a special container that has the perfect amount of space for the item, but no extra space whatsoever. The container does, however, have a place for locks on the outside.

    You have locks and keys, but your acquaintance does not have keys to unlock any of your locks. How can you send the extremely valuable container using your lock and have your acquaintance eventually be able to open the package?

  9. Treacherous: In a remote country ruled by a brutal monarch, a man was sentenced to death. Feeling godly, the brutal monarch told the man he would allow one final statement.

    The monarch advised the man that if he lied in his final statement, he would be drowned, but if he told the truth in his final statement, he be shot by firing squad. The man thought, and made his final statement. Due to the statement, the monarch was forced to release the man unharmed. What could the man possibly have said?

  10. Treacherous: There is an English word that is nine letters long that can form a new word each time one letter is removed. In fact, it can change to a new word every time a letter is removed until only one letter remains. What is the word, and what is the sequence of words formed by removing one letter at a time?

Logic puzzle answers

  1. Once. After that, the mathematician would be subtracting ten from 90, then 80, then 70 . . .
  2. Three wise men
  3. They were part of a set of triplets, the third child being a daughter
  4. 5 + 5 4 5 = 550 (add one diagonal line to the second “+” to make it a “4”)
  5. Alexander juggled the gold as he crossed the bridge, keeping at least one piece in the air at all times.
  6. One person stands on one corner of the handkerchief and closes a door. The second person stands on the corner of the handkerchief protruding under the door. With the door between them, they cannot possibly touch.
  7. The person is on tracks in a railroad tunnel walking toward the train and is close to the end when the oncoming train is discovered. The person must then run forward to clear the tunnel before the train enters.
  8. You send the container with one of your locks securing the container. Your acquaintance receives the container, and without trying to open it, attaches his lock next to your lock. He then sends the container back to you.

    You use your key to unlock your lock, remove it, and send the container back to your acquaintance with only his lock on the container. He can then open the container using his own key to his own lock.

  9. The man said, “I will be drowned.”
  10. The word is STARTLING and the word sequence is: STARTING STARING STRING STING SING SIN IN I