I was first introduced to the proof is in the pudding brainteaser in a book I was reading. I read the puzzle, puzzled over it for a few minutes, considered looking up the answer in the back of the book, and decided against it.
A few weeks ago, Fawn mentioned that this puzzle was one of her favorites on Twitter. I commented saying that I had never been able to figure it out. She recommended that I give it another try. I did, and this time I was able to figure it out!
Here’s how the puzzle goes according to The Math Forum:
During a recent census, a man told the census taker that he had three children. When asked their ages, he replied, “The product of their ages is 72. The sum of their ages is the same as my house number.”
The census taker ran to the door and looked at the house number. “I still can’t tell,” she complained. The man replied, “Oh that’s right, I forgot to tell you that the oldest one likes chocolate pudding.”
The census taker promptly wrote down the ages of the 3 children. How old are they?
This puzzle is also known as the Census Taker Puzzle.
I used to think this puzzle was impossible, but I promise it’s not. I’m not going to link to a solution because I think you should try to figure it out for yourself! Some research online says that the original riddle should be attributed to George Polya.
I intentionally do not share solutions to the puzzles I feature on my website because I strive to provide learning experiences for my students that are not google-able. I would like other teachers to be able to use these puzzles in their classrooms as well without the solutions being easily found on the Internet.
However, I do recognize that us teachers are busy people and sometimes need to quickly reference an answer key to see if a student has solved a puzzle correctly or to see if they have interpreted the instructions properly.
If you are a teacher who is using these puzzles in your classroom, please send me an email at email@example.com with information about what you teach and where you teach. I will be happy to forward an answer key to you.