Three kittens and three puppies ate twenty sausages. The red kitten ate the most, and the gray one ate the least. Could it be that the puppies ate no less sausages than the kittens?

Leaflet #difficult_situation

🎞 The Futurama Theorem

There are at least ten liters of water in the tank. Is it possible to collect six liters with a nine-liter bucket and a five-liter can?

Leaflet #difficult_situation

🎞 9.999... really is equal to 10

A peasant needs to ferry a wolf, a goat and cabbage across the river. But the boat is such that only a peasant can fit in it, and with him either only a wolf, or only a goat, or only cabbage. But if you leave a wolf with a goat without a peasant, then the wolf will eat a goat, if you leave a goat with cabbage, then the goat will eat cabbage. What to do?

Leaflet #difficult_situation

More about this river crossing puzzle

A woman picked apples in the garden. To get out of the garden, she had to go through four doors, each of which was guarded by a fierce guard who took away half of the apples. She brought home 10 apples. How many apples did the guards get?

Leaflet #reverse_course

📑 Science or prayer?

An alley of trees was planted in a row in the park. A year later, another one was planted between any two neighboring trees. A year later they did the same. There were 1197 trees. How many were there initially?

Leaflet #reverse_course

🎞 The Unbeatable Game from the 60s: Dr NIM

Two pirates were playing for gold coins. First, the first lost half of his coins and gave them to the second, then the second lost half of his coins to the first, then again the first lost half of the coins. As a result, the first turned out to have 15 coins, and the second 33. How many coins did each of the pirates have before the game started?

Leaflet #reverse_course

One lily bloomed on the lake. Every day the number of flowers on the lake doubled, and on the 20th day the whole lake was covered with flowers. On what day was the lake half covered with flowers?

Leaflet #reverse_course

🕊 Twitter

The following operations can be performed with numbers: multiply by two or randomly rearrange the numbers (you can't just put zero in the first place). Is it possible to get 74 out of 1 using such operations?

Leaflet #reverse_course

🥳 4th of August: John Venn's Birthday

English mathematician and logician John Venn was born in 1834. He is especially famous for introducing the "Venn diagrams" used in set theory and logic. Venn Diagram uses circles to visually and logically sort groups to illustrate their relationships to each other.

#celebration

All natural numbers from 1 to 1000 were written in the following order: first, the numbers whose sum of digits is 1 were written out in ascending order, then, also in ascending order, the numbers with the sum of digits 2, then the numbers whose sum of digits is 3, etc. In what place was the number 996?

Leaflet #reverse_course

In the classroom of the math club, all the children who went there were given chocolates. The first visitor was given one chocolate bar and a tenth of all the remaining ones, the second visitor was given two chocolates and a tenth of the remaining ones, ..., the ninth visitor was given nine chocolates and a tenth of the remaining ones. After that, Sheldon came running, but, unfortunately, the chocolates were already over. How many chocolates did the children get?

Leaflet #reverse_course

There are 20 one-dollar coins and 20 half-dollar coins in the piggy bank. What is the smallest number of coins to take out of the piggy bank so that
1) two identical coins are sure to be among them?
2) two one-dollar coins are sure to be among them?
3) two different coins are sure to be among them?

Leaflet #money

Two hostesses bought milk every day for a month. The price of milk varied daily. The average price of milk for the month was $4. Each day the first hostess bought one gallon, and the second bought $4 worth of milk. Which one spent more money during that month and which one bought more milk?

Leaflet #money

There are nine coins, among them one counterfeit. The real coins all weigh the same, but the fake one weighs a little less. How can you use a cup scale without arrows and weights to determine a counterfeit coin in two weighings?

Leaflet #money

Pinocchio planted a money tree, and instead of leaves, gold coins appeared on it every day. The first day one coin appeared on the tree, the second day two, the third day three, and so every day it grew one more coin than the previous day. On the night of the 29th to the 30th day, Alice the Fox and Basilio the Cat came and ripped off all the gold coins. How many coins did the treacherous Alice and Basilio get?

Leaflet #money

The young man agreed to work on the condition that at the end of the year he would receive a Ford F-150 and $26,000. But at the end of 8 months, he quit his job and received a Ford F-150 and $10,000. How much was the Ford F-150 worth?

Leaflet #money

Two people play a game like this. They take turns putting the same coins on the round table. You can't put coins on top of each other. The loser is the one who has nowhere to put the next coin. Which player is guaranteed to win: the beginner or his opponent? How should he play?

Leaflet #money

There are coins on the table. Fifteen of them are eagle up and the rest are eagle down. Blindfolded, you have to put these coins into two piles so that the number of coins lying eagle up in these piles is the same. The number of coins in the piles can be different (the pile can consist of any number of coins, including one or even less), the coins can be turned over, but it is impossible to determine by touch how a coin lies.

Leaflet #money

Cut the square into a) 4; b) 9; c) 17 squares.

Leaflet #cut

Four dwarfs inherited from their uncle an orchard enclosed by 16 matchsticks with 12 fruit trees. The location of the trees is shown in the drawing. Divide the garden using 12 matches into four equal parts containing an equal number of trees each. The matches are only allowed to be placed on the dotted lines. (Equal parts must have the same shape, size, and same arrangement of trees.)

Leaflet #cut