Get One Hundred
9 8 7 6 5 4 3 2 1 = 1 0 0
Add 3 pluses and 1 minus (not necessarily in that order) anywhere above in order to get a valid equality.
SOLUTION
The answer is:
9 8-7 6+5 4+3+2 1 = 1 0 0
Black-White Maze
Find your way through this black-white maze, created by William Leonard.
SOLUTION
The solution is shown below.
FEATURED
Lost In the Forest
You are lost in the middle of a forest, and you know there is a straight road exactly 1 km away from you, but not in which direction. Can you find a path of distance less than 640 m which will guarantee you to find the road?
SOLUTION
Imagine there is a circle with a radius of 100 m around you, and you are at its center O. Let the tangent to the circle directly ahead of you be t. Then, follow the path:
- Turn left 30 degrees and keep walking until you reach the tangent t at point A for a total of 100×2√3/3 meters, which is less than 115.5 meters.
- Turn left 120 degrees and keep walking along the tangent to the circle until you reach the circle at point B for a total of 100×√3/3 which is less than 58 meters.
- Keep walking around the circle along an arc of 210 degrees until you reach point C for a total of 100×7π/6 which is less than 366.5 meters.
- Keep walking straight for 100 meters until you reach point D on the tangent t.
An Ant’s Path
An ant is positioned at one of the vertices of a cube and wants to get to the opposite vertex. If the edges of the die have length 1, what is the shortest distance the ant needs to travel?
SOLUTION
We unfold a cube to get a cross-shaped figure. Then, the problem is to find the shortest path between two points separated by a horizontal distance of 2 units and a vertical distance of 1 unit.
It is easy to see that the path in question is the one passing through the middle of the edge between the start and end points, and which has a distance of √5.
Dr. Riesen’s Rebuses 1
Can you figure out what these love-related expressions these rebuses represent?
SOLUTION
The answers are:
- Be mine
- Love at first sight
- True love forever
- Love is in the air
- Romance
- Sweet nothings
- XOXO
- Written in the stars
- Sweetheart
- Love birds
- Heart throb
- Pucker up
- Love is love
- You complete me
- Lover’s gaze
- Love struck
FEATURED
Kings and Queens
What should follow the sequence of diagrams shown below?
SOLUTION
The diagrams represent consecutive monarchs of England:
- King Edward the 8-th → Ke8
- King George 6-th → Kg6
- Queen Elizabeth 2-nd → Qe2
Therefore, the next diagram should represent King Charles the 3-rd → Kc3.
A Square and an Invisible Point
There is a square drawn on a piece of paper and also a point marked with invisible ink. You are allowed to draw 3 lines on the paper and for each of them you will be told whether the point is on its left, on its right, or lies on the line. Your task is to find out whether the point is inside the square, outside the square, or on its boundary. How do you do it?
SOLUTION
Draw one of the diagonals of the square. Then, draw the 2 lines containing the sides of the square that are on the same side as the invisible point.
It Turns Into a Different Story
It turns into a different story. What is it?
ANSWER: ✱✱✱✱✱✱ ✱✱✱✱✱✱✱✱✱
Note: This is Will Shortz’s favorite crosswords clue of all time.
SOLUTION
The answer is SPIRAL STAIRCASE.
The Hardest Mate in 2
White to play and mate in 2.
Note: Magnus Carlsen spent almost 2 minutes solving this puzzle.
SOLUTION
The first move is 1. Qa8. If Black plays Qd4, then White responds with Re3#. Otherwise, White plays either Nc5# or Nd6#, so that Black cannot capture the Knight neither with the Rook or the Queen.
Touch or Don’t Touch
For this puzzle/game, you need to keep presenting various words to your friends and telling them whether they are “TOUCH” or they are “DON’T TOUCH”. Below, we have listed several words from each category.
TOUCH: banana, proof, mouse, keyboard, promo, woman
DON’T TOUCH: cherry, solution, cat, screen, discount, girl
Can you guess what determines whether a word is “TOUCH” or “DON’T TOUCH”?
SOLUTION
Words that make your lips touch when pronounced belong to the “TOUCH” category, while the others belong to the “DON’T TOUCH” category. The sounds “P”, “B”, “M”, and “W” that cause this are called “bilabial”.