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Posts by will.octagon.gibson
Draw 3 lines, not necessarily straight, connecting the dots and satisfying all the following conditions: No line may touch or intersect another line. Every line must be completely inside the ci...
Imagine you are on a planet the same size as Earth but this planet is perfectly spherical and solid everywhere. Furthermore assume it has a North and a South Pole just like Earth and has direction...
There seems to be a bug in how some isolated letters are displayed in a code block. This bug affects how the letters a, b, i, p, and q are displayed. These letters are being bolded without even b...
In the diagram below we have pentagon ABCDE with 5 edges and 5 diagonals. These 10 line segments are currently all colored black. The diagram contains several triangles but for this puzzle we are...
An Amazon is a fairy chess piece that can move like a queen or a knight. What is the maximum number of Amazons that can be placed on a 5x5 chessboard so that no piece attacks another? Attribu...
Here’s one possible solution: Click/tap here to reveal I discovered this solution by trying to solve related problems with fewer line segments. Here’s an even simpler solution: ...
Draw 8 straight line segments so that each line segment intersects with exactly 3 other line segments.
There are $100$ marbles in a bucket. Alpha and Beta play a game in which they take turns removing marbles from the bucket with Alpha going first. At each turn the player can choose to remove eith...
Find the pattern in the fingers:
Here’s an expression similar to Moshi’s: Spoiler! Click here to reveal $$\LARGE 2^{1^{34567890}}$$ Here’s an expression with a single division: Spoiler! Click here to reveal $$\LARGE \frac...
Using all the integers from 1 to 10 inclusive (each used exactly once), along with any number of the four arithmetic operations (add, subtract, multiply and divide) and parentheses, construct an eq...
Canoe, Wrote, Teacher, Runoff, Verify, Exist, Inverse, Tighten, ? What meal can come next in the above list? Choose your answer from the options below and explain your choice: Breakfast, Brunch,...
What’s the next number in the following sequence: 0, 4, 8, 21, 52, 65, 96, ?
I think optimization puzzles like A knight's sightseeing tour are fine here. If an answer to an optimization question is correct but doesn’t prove that the answer is optimal, I think that’s fine. ...
This puzzle was exactly the right level of difficulty for me. Solution! Click/tap here to reveal In solving this puzzle, I treated the middle triangle as the bottom face of the tetrahedron. Th...
For me, this puzzle was the right level of difficulty; not too easy and not too hard. To solve this puzzle I used intelligent trial and error. To reduce the number of possibilities I used the fac...
I would love to see Puzzles promoted to its own community. I would also love to see more people submit puzzles.
Place an X into seven of the squares so that no square marked with an X is halfway between two other squares that are also marked with an X.
Solution In Roman numerals the number five is represented by V. Here are 5 copies of the Roman numeral five:
In the diagram below, the number five is made up of 5 identical line segments. Reposition the line segments so the number five appears 5 times. You are not allowed to do anything except moving th...
In some Mathematical puzzles, there are several unknown values. In this particular puzzle, there are 12 unknown numbers that are to be placed in the 12 empty squares. We could attempt to solve th...
Eight different dominoes lie on a plane. No boundaries between the dominoes are shown in the figure. Draw these boundaries. Clarifications: A domino is made up two square halves joined at a com...
A solution that uses all 6 numbers $\Large \frac{75}{3} \times 25 \ + \ \frac{100}{50} \times 7 = 639$
There are 6 permutations of the numbers 1, 2, 3. They are: 123 132 213 231 312 321 The goal is to make a string (as short as possible) using the digits 1, 2 and 3 so that each of the abov...
A large whiteboard has 2014 "+" signs and 2015 "−" signs written on it. You are allowed to delete two of the symbols and replace them according to the following two rules. If the two deleted symbo...
