# Category Information

I have tried to find some papers about Silva Method when that i seen this text in Wikipedia: James Randi wrote that the Silva Method "claims to develop improved memory, learning ability, and

Pedro's mother picks him up every day from school with the car. The mother always leaves the house with the car at the same time, picks it up at the door of the school at 5:30 and returns home on the same road, using the same time both on the way out and on the way back, So they always arrive at the same time home.
It is good to know that the value of diamonds increases according to the square of their weight just as the value of rubies does according to the cube of their weight. Thus, for example, if a carat diamond is worth \$ 100 one of two carats of the same quality will cost \$ 400 while one of three carats of equal purity will cost \$ 900.
Can you solve this problem as quickly as Einstein? Solution We represent the orange with the letter n, the banana with the p, the cherries with the c and the melon with the m. i) 4 xn = 28 ii) 2 xn + 2 xp = 30 iii) p + c + m + n = 20 iv) 2 m + c + p = 16 From i) we get that n = 7, from ii) that p = 8 and from iii) and iv) that m = 3 and c = 2.
Write in each of the 9 boxes of a board of size 3 x 3 one of the figures 1, 2 or 3, so that the sum of the figures written in each row, column and in any diagonal of the square is equal to 6. No number can be repeated in each row, column or diagonal. Solution There are several different solutions.
A snail ascends a slippery wall one meter high. The snail advances three centimeters every minute and stops for another minute to rest, during which it slips and falls two centimeters. How long will the snail take to climb the wall? Solution The snail will take 195 minutes to climb the entire wall.
Three suspects were undergoing an interrogation to locate the only one who was guilty of a robbery. Each of the three accused one of the other two. Of them, only the first told the truth. Pressed by the police, they returned to testify and now each accused someone different and no one self-accused.
The library of my town is very small and the books are distributed in three categories only: Novel, Science and children. Half of the books are novels, there are 101 books in the science section and 99 in the children's category. How many books does the library have? Solution If we know that half of the books are novels and we have 200 books from the other categories, there will be as many novels in the library and therefore we will have 400 books in total.
Express the number 30 with three equal figures and with the signs of the operations you have used to find it as many times as you can. Solution 5 x 5 + 5 = 30 6 x 6 - 6 = 30 33 - 3 = 30 XXX = 30
The middle ham is a game for three people. The cards from 1 to 9 of one of the four suits of the deck are mixed and then three cards are distributed to each of the players. In secret, each one adds his three cards and wins the one that has the sum that is right in the middle. In a game, a player receives his three cards and before his teammates show their scores he jumped for joy and exclaimed: I won!
If a square measuring 1 meter side is divided into squares of 1 decimeter side, how long would these squares be if we put them in a straight line? Solution It would have 10 meters. The number of squares that would fit inside is 100, since a square decimeter (symbol: dm²) is a unit of surface that occupies a square of a decimeter of side.
A soldier falls prey to enemy troops. An evil executioner proposes a macabre game: the soldier must decide between dying hung or shot dead. But the executioner tells him first that he must pronounce a sentence and that, if it is true, he will die shot, but if it is false, he will die hanged. How is it possible that the soldier can escape his sad fate?
In a game for two players, 23 sticks are placed on a table and each opponent will alternately take one, two or three sticks at a time, as they prefer. The player who is forced to take the last stick will lose. What strategy can be followed to always win? Solution The player who leaves the last five sticks will win because his opponent must take 1, 2 or 3 and leave 4, 3 or 2 sticks respectively on the table so it will be enough to take 3, 2 or 1 to leave a single stick that the other player will take.
Bethlehem invited seventeen friends to his birthday party. Each one was assigned a number from 2 to 18, with 1 being reserved for her. When everyone was dancing, he realized that the sum of each couple's numbers was a perfect square. What is the number of the couple in Bethlehem? Solution The highest number that can be reached by adding those that Bethlehem has distributed is 35 = 17 + 18, and the lowest number 3 = 1 + 2.
Write any three-digit abc number (the first and the last must be different). Then invert the number (cba) and calculate the difference between them. To this result add the obtained by investing it. Solution Check that it always gives 1,089
Mari Luz has twice as many brothers as sisters, but if the total number of brothers we subtract all the sisters in the family, including her, this number gives a result of three. How many brothers and sisters are in the family? Solution Eight brothers and five sisters.
My friend Rodrigo lives in apartment number 28 that is on the 6th floor of the building. Going up the stairs I see that there are no apartments on the ground floor and that each of the floors has the same number of doors. How many apartments are on each floor? Solution Each floor has 5 apartments.
Three ridiculous sisters always answer the following questions when asked about age: The square of Ana's age plus the square of Blanca's age plus Carla's age is equal to the square of Carla's age. When Ana is the age of Carla now, Carla will be 4 times the age Ana is now and twice the age of Blanca now.
An island is inhabited by two kinds of people: gentlemen who always tell the truth and the rogues who always lie. The three inhabitants of the island: Adrián, Benjamín and Conrad are talking: Adrián says: - We are all rogues. But Benjamin rectifies him and says: - Exactly one of us is a gentleman.
A fly travels walking at a constant speed along a 10cm long ruler. Advance from the 10cm mark and take 10 seconds to reach the 5cm mark. How long will it take to reach the 1cm mark? Solution The fly initially travels 5 cm (from the 10cm mark to the 5cm mark) in 10 seconds so it walks at a speed of 1cm every 2 seconds.
Place the numbers from 1 to 14 in the heptagon that appears on the left so that the sum of the three numbers of each edge of the heptagon is 26. Solution There are many solutions, here are some of them. Starting with the position marked with the letter A and writing the numbers clockwise we have: 14,1,11,2,13,5,8,6,12,4,10,7,9,3 14,2,10 , 3,13,4,9,5,12,6,8,7,11,1 14,2,10,4,12,1,13,5,8,7,11,6,9,3