# Category In details

Japanese engineer Akira Haraguchi, born in 1946, is known for memorizing and reciting digits of the Pi () number. He sees the memorization of the Pi number as "the religion of the universe" and as an expression of his lifelong pursuit of eternal truth. It reached the 100,000-digit world record after 16 hours of recitation, starting at 9am on October 3, 2006 and ending at 1:28 am the next day.

Number that makes the equation true Difficulty level: Replace the asterisk (*) with a natural number so that the subtraction below is true. Challenge 24 Put the Soldiers in Queues Challenge Index Next >> Challenge 26 Bricks in the Truck
Who did not pay the entrance? Difficulty Level: Four friends go to the museum and one of them enters without paying. A prosecutor wants to know who was penetrating him: -– I didn't go, says Benjamin. -– It was Pedro, says Carlos. -– It was Carlos, says Mario. -– Mario is not right, says Pedro. Only one of them lied. Who did not pay the entrance?
Share apples among children Difficulty level: Divide 9 apples among 12 children so that no apples are divided into more than 4 parts. Challenge 47 Cup Sugar Bags Challenge Index Next >> Challenge 49 Balls in the Box
Divide the wine among the drunks Difficulty Level: Two drunken friends bought 8 liters of wine. They were walking, and halfway down, they decided to separate, but to divide the wine evenly. To make the measurements there is an 8 liter barrel (where is the wine), a 5 liter can and a 3 liter one.
The Stubborn Frog Difficulty Level: Fetching water, a frog fell into a 30 meter deep pit. In her quest for survival, the stubborn frog was able to climb 3 meters each day, and night fell and fell 2 meters. How many days did the frog take to get out of the well? Challenge 45 The Spider Web Challenge Index Next >> Challenge 47 Cup Sugar Bags
Chicken eggs Difficulty level: Luiz Eduardo bought several champion chickens in laying eggs. In testing the efficiency of the chickens, he observed that every minute the number of eggs in the basket doubled. At two o'clock the basket was full. What time was the basket half full? Challenge 61 Ship Ladder Challenge Index Next >> Challenge 63 Octagenarian and His Great-grandson
Represent numbers 2 through 9 Difficulty level: Represent numbers 2 through 9 using ALL digits 0 through 9. Example: 2 = 13584/06792 3 = ??? 4 = ??? … 9 = ??? Challenge 71 The Hungry Moth and the 10 Books Challenge Index Next >> Challenge 73 Number 6 with 3 equal digits
The bottle and the cork Difficulty level: A bottle with its cork costs \$ 1.10. Knowing that the bottle costs \$ 1.00 more than the cork, what is the price of the cork? And what is the price of the bottle? Challenge 66 The dog and the hare Challenge index Next >> Challenge 68 Sum of the digits
Complete the Letter Sequence Difficulty Level: Considering the official alphabet, which does not include the letters K, W, and Y, complete the series below: BDGLQ… Challenge 92 Reducing Inmates' Penalties Challenge Index Next >> Challenge 94 churros
Serginho crossing the bridge Serginho waited for the policeman to sleep and walked halfway across the bridge. When the policeman was waking up, Serginho turned his back and made him walk in the direction he had come. Then the policeman said to him, "Come back, you can't cross the bridge!" And Serginho returned, thus following his path.
The king and the slaves Brown eyes - the slave speaks the truth Blue eyes - the slave lies If the first slave has brown eyes, he will say that he has brown eyes. If the first slave has blue eyes, he will say that he has brown eyes (for they lie). In asking the second slave in line, he replied that the first had said he had blue eyes.
5-digit palindromes Level of difficulty: A palindrome number is one that is equal when read back to front and back to front. For example, 171 is a palindrome number. There are 90 three-digit palindromes. How many 5-digit palindromes are there? Challenge 79 Aguiar's children Challenges index Next >> Challenge 81 Restaurant surprise
The gold of the traveler He must cut the first time, so that the first piece should have 1/7 (one seventh) of the total bar. Then it should cut for the second and last time, each part having respectively 2/7 (two sevenths) and 4/7 (four sevenths) of the total bar. Then, the payment must be made as follows: 1st daily: paid with 1/7 of the bar.
Forming the Number 100 Difficulty Level: Form the number 100 using the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, the +, -, *, /, signs, and parentheses if necessary. Challenge 87 How old was Claudiomiro? Challenges Index Next >> Challenge 89 The Eight Eights
Complete the sequence of letters S, T, Q, Q, S, S, D. These are the days of the week. Back to statement Challenge 106 Radigunda needs money Challenge index Next >> Challenge 108 The rooms and the lamps
Half Thirteen In Roman numerals, thirteen is XIII. Making a horizontal cut in half of that number gives VIII, which is eight in Romans. Back to statement Challenge 114 Eight Queens on the Chessboard Challenge Index Next >> Challenge 116 Digging a Hole
Resignation of Night Guard Night guards should not sleep on duty. Back to statement Challenge 126 Aligning the Points Challenge Index Next >> Challenge 128 Nine Challenge
Birthdays and probability The probability of 40 people not having a birthday on the same day of the year is approximately: Therefore, the probability of at least two people having a birthday on the same day of the year is approximately: 100% - 10.9% = 89.1%. . Back to statement Challenge 110 Traveler's Gold Challenge Index Next >> Challenge 112 The Guava Critter
Hosting with Friends Carlos Recife 305 Fernando Porto Seguro 419 Joel Fortaleza 538 Back to statement Challenge 120 Fire on the rope Challenge index Next >> Challenge 122 How much should a jeweler pay?
The Fly and the Cyclist As the two cyclists travel 20km in an hour and were initially 40km apart, they found themselves cycling for an hour. As the fly flies at 30km / h, it traveled 30km. Back to statement Challenge 116 Digging a hole Challenge index Next >> Challenge 118 Dividing the Camels