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