Tic-Tac-Toe Loser
How many X’s can you place the most on a tic-tac-toe board without getting 3 X’s on a line?
SOLUTION
You can place 6 X’s without getting 3 X’s on a line, as shown below.
Hidden Words Animals
Find all the hidden words in the grids.
SOLUTION
The solutions are shown below.
Circular Racetrack
Suppose you are on a one-way circular racetrack. There are 100 gas cans randomly placed on different locations of the track and the total amount of gas in the cans is enough for your car to complete an entire circle. Assume that your car has no gas initially, but you can place it at any location on the track, then pick up the gas cans along the way and use them to fill the tank. Show that you can always choose a starting position so that you can complete an entire circle.
SOLUTION
Imagine you put your car at any location, but instead with an empty tank, you start with enough gas to complete the circle. Then, simply track the amount of gas you have and locate the point on the track where it is the lowest. If you choose that location as a starting point, you will be able to complete the track.
A Short, Brutal Riddle
Left alone, I’m a word with five letters.
I’m honest and fair, I’ll admit.
Rearranged, I’m of no use to trains.
Again, and I’m an overt place, warm and well lit.
What am I?
SOLUTION
The answer is LIAR. After rearranging the letters, you can get RAIL – important for trains, or LAIR – a dark, hidden place. Since the riddler is a liar, the resulting words are exactly the opposite of his descriptions.
Source:
Send More Money
Replace every letter with a different digit between 0 and 9, such that you get a correct calculation.
SOLUTION
The answer is 9567 + 1085 = 10652.
You can first see that M = 1. Then S = 8 or 9 and O = 0. MORE is at most 1098, and if S = 8, then E = 9, N is either 9 or 0, but this is impossible. Therefore S = 9, N = E + 1. You can check easily the 6 possibilities for (N, E) and then find the answer.
Bus Driver’s Age
Imagine you are driving a bus. At the first stop, 3 people get on the bus. At the second stop, 5 more get on. At the third stop, 2 get out and 4 get on. At the last stop, everybody gets out. How old is the bus driver?
SOLUTION
You are imagining the story, so the bus driver is as old as you.
Coins and Cups
How can you put ten coins in three plastic cups, so that in every cup there is odd number of coins?
SOLUTION
Drop five coins in the first cup. Than put the other two cups in each other and drop the five remaining coins in them.
Puzzle Sum 26
What animals do these sums spell?
SOLUTION
SCOOP – COOP + NAIL = SNAIL
FOWL – OWL + OX = FOX
Avoiding Bad Luck
You are walking alone on the sidewalk. There are no stars on the sky, no moonlight, all of the lamps on the street are broken, you don’t carry any source of light with you and there aren’t any cars or other people approaching. A silent black cat tries to cross your way, but you somehow spot it and turn around in order to avoid bad luck. How did you see the cat?
SOLUTION
All of this happened during a (cloudy) day.
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Sum Up to 15
Tango and Cash are playing the following game: Each of them chooses a number between 1 and 9 without replacement. The first one to get 3 numbers that sum up to 15 wins. Does any of them have a winning strategy?
SOLUTION
Place the numbers from 1 to 9 in a 3×3 grid so that they form a magic square. Now the game comes down to a standard TIC-TAC-TOE, and it is well-known that it always leads to a draw when both players use optimal strategies.
