Insert the missing parentheses into each equation to make it true.
The solutions are:
“Intermediate Algebra for College Students” by Karl. J. Smith and Patrick J. Boyle
Reach the Goal by following the cats, alternating between cats facing forwards and cats facing backwards. The cats in your path must be connected or overlapping.
The path is outlined via the green cats below.
The main challenge of a Sunome puzzle is drawing a maze. Numbers surrounding the outside of the maze border give an indication of how the maze is to be constructed. To solve the puzzle you must draw all the walls where they belong and then draw a path from the Start square to the End square.
The walls of the maze are to be drawn on the dotted lines inside the border. A single wall exists either between 2 nodes or a node and the border. The numbers on the top and left of the border tell you how many walls exist on the corresponding lines inside the grid. The numbers on the right and bottom of the border tell you how many walls exist in the corresponding rows and columns. In addition, the following must be true:
Examine the first example, then solve the other three puzzles.
The solutions are shown below.
One day, the police finds a dead man inside a hut, with a bullet in his head. In his left hand, the man is holding a gun. In his right hand, he has a recording. When the recording is played, the police hears the man talking about how horrible his life has been and how he wanted it to end. The recording ends with a gunshot. The police are about to call it a suicide until a detective points out an important clue. What is it?
If the person shot himself and died, he wouldn’t have been able to stop the device from recording further.
The Cipher Solver Series is a collection of cipher puzzle books, written by D. H. Bernhardt. Each of the books teaches about various cipher techniques and then provides examples that help the reader master them. So far, there are 3 volumes released, and a fourth one is on its way.
Each book in the series starts with a short history on ciphers. Then, it provides 2 chapters on how to encode and decode specific ciphers, followed by 2 chapters with puzzle-examples. Finally, the books end with hints and solutions.
Volume 1 and 2 focus on the so-called Route and Rail ciphers, while volume 3 introduces us to the Pen and Polybius ciphers. The former are examples of transposition ciphers, those are ciphers in which the symbols are preserved, but their order is scrambled. The latter are examples of substitution ciphers, those are ciphers in which the original symbols are replaced with new ones.
The following example of a Rail cipher is taken out of the first book in the series. Let’s say the task is to encode the phrase “Beware of the attack from the North”. To do that, we create a rectangular grid and starting from the top left corner, we enter the letters of the phrase in a zigzag manner. We add some “X” letters at the end as padding, if necessary. This results in a route-like structure inside the grid, consisting of alternating diagonal rails.
Then, if we read the letters line by line, top to bottom, we get the encryption:
BOCT TXEE FAKM HRHX XWRA TFOE OXXA TRNX
To decrypt an encoded phrase, we just need to determine the dimensions of the grid and the size of the rails of the route. You can practice your route ciphering skills with the following puzzle from the book:
The transposition ciphers are fun but quite easy to solve, especially the Route ciphers. They all have been chosen with identical grid widths, so the only unknowns there are the route rails sizes. I recommend getting just one of the first two volumes, since the novelty in the second one lies mostly in the introductory chapter.
The two substitution ciphers are harder to solve and require more careful analysis. However, it is worth noting that the decoding procedure works identically for both of them, even though the ciphers use different encryption symbols.
Despite the remarks above, I think the books are educational, well-structured, and would be engaging to new cipher enthusiasts. I hope once the author completes his series, he considers combining the content in one larger edition divided into sections based on cipher type, such as transposition and substitution.
The streets of the city are a square grid that extends infinitely in all directions. One of the streets has a police officer stationed every 100 blocks and there is a robber is somewhere in the city.
Can you devise a strategy that guarantees the robber will be spotted by a police officer at some point, no matter how he tries to avoid them?
Note: The officers can see infinitely far, but their running speeds are lower than the speed of the robber.
Let the police officers are located at points with coordinates (100N, 0) for N = 0, ±1, ±2… First, we fix the positions of all officers stationed at points (±200N, 0), then repeatedly perform the following procedure, step by step:
On step M, we let the non-fixed officers who are closest to the center move to the free points with coordinates (K, 0) and (0, K) for K = 0, ±1, ±2, … ±M. Then we fix their positions.
Since there are fixed officers at points (200N, 0) at all times, the robber is contained within some vertical strip the entire time. Therefore, at some point there will be two fixed officers that will restrict the robber within a horizontal segment of size 1, at coordinates (x, T) for x ∈ (S, S+1) and some T. Finally, at some point an officer will move to the point (0, T) and will spot the robber.
“The Password Game” is a new web puzzle/game by Neal Agarwal, a Brooklyn-based software developer, popular for various fun projects hosted on his website Neil.Fun.
pon opening the game webpage, you are given the seemingly simple task of creating a password. The password, in order to be strong enough, needs to satisfy a list of conditions. The first few of them are common; there is a minimum length and special characters should be included. However, after complying with every rule on the screen, a new one appears, more complex and bizarre than the previous one. This forces you to constantly make changes to the increasingly lengthy password, while trying to resolve any conflicts that appear.
The Password Game is quite difficult. On our first try, we failed the game after not giving in a timely manner a bug emoji 🐛 to a chicken emoji 🐔 inside our 70+ character password, while simultaneously looking for a YouTube video of the exact runtime of 19 minutes and 34 seconds. Hopefully, you can do better.
If you enjoy “The Password Game”, you can take a look at Neil’s other creations, such as “The Absurd Trolley Problems”, which offers sinister twists on the famous Trolley Problem.
A very rich man has many servants in his mansion. One day as he is about to travel, his night watchman warns him not to board his flight. “I had a dream last night that the plane crashed,” the watchman tells him. The rich man is annoyed at first, but since he is also superstitious himself, he decides not to take the flight.
Later that day as he is watching the news, he sees that his plane did, in fact, crash. He goes over to thank and reward his servant, and then fires him. Why?
The watchman has been sleeping at work instead of guarding the mansion, so that’s the reason he gets fired.
Move the minus sign to make an expression equivalent to nine fifty.
Move the minus sign to the top of the second vertical line to get “10 to 10”, i.e. 9:50.
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