Updated: 2023-11-30 01:27:51
I recently posted the following polyomino puzzle, and my readers are asking for a solution. Puzzle. You are given a 5-by-7 rectangle with two corners cut out: A 1-by-1 tile is cut from the bottom left corner, and a 1-by-2 tile is cut out of the top right corner, as pictured. The task is to […]
Updated: 2023-11-28 18:52:00
A new geometry problem from my friend, Alexander Karabegov. Puzzle. A convex quadrilateral is inscribed in a rectangle with exactly one quadrilateral’s vertex on each side of the rectangle. Prove that the area of the rectangle is twice the area of the quadrilateral if and only if a diagonal of the quadrilateral is parallel to […]
Updated: 2023-11-22 17:04:56
Here is another STEP homework question, which is a famous riddle. Puzzle. Peter had ten cows. All but nine died. How many cows are left? The wording is confusing on purpose. So, the students who are in a hurry subtract nine from ten and answer that only one cow is left. This answer is wrong. […]
Updated: 2023-11-21 20:17:27
I love the game of SET, where you have a specialized deck of 81 cards. The image on each card has four features: color, shape, shading, and the number of objects. Each feature can have three possible values. Three cards form a set if, for every feature, the values on the cards are either all […]
Updated: 2023-11-19 20:27:44
I deleted my previous post about Solomon’s knot. The reason is simple. I made the mistake of trusting Wikipedia. I was sure that the linking number of Solomon’s knot was 2. Then Wikipedia said it was 0, so I fixed “the error” in my post. One of my readers corrected me. So, I rechecked it, […]
Updated: 2023-11-10 17:46:06
Puzzle. A group of 20 students formed a line to take an oral exam with Professor Chill. They were afraid to enter the classroom, so they decided to do a drawing. They wrote the numbers from 1 to 20 on pieces of paper, placed them in a hat, and each student picked one. The student […]
Updated: 2023-11-08 01:46:48
A quine is a computer program which takes no input and produces a copy of its own source code as its only output. Puzzle. Assuming English is a computer language, write a quine in English. My students had many solutions on how to solve this puzzle. They were all variations on “Write this sentence.” This […]
Updated: 2023-11-03 16:28:53
What’s a polyomino? A polyomino is a plane geometric figure formed by joining one or more equal squares edge to edge. Here, we have a puzzle about a polyomino that is almost a rectangle. Puzzle. You are given a 5-by-7 rectangle with two corners cut out: A 1-by-1 tile is cut from the bottom left […]
