Three friends – Peter, Ryan and Sarah – are university students, each studying a different subject from one of the following: mathematics, physics or chemistry. If Peter is the mathematician then Sarah isn’t the physicist. If Ryan isn’t the physicist then Peter is the mathematician. If Sarah isn’t the mathematician then Ryan is the chemist. Can you determine which subject each of the friends is studying?
In the first pencil case, there is a lilac pen, a green pencil and a red eraser; in the second – a blue pen, a green pencil and a yellow eraser; in the third – a lilac pen, an orange pencil and a yellow eraser. The contents of these pencil cases are characterised by such a pattern: in every two of them exactly one pair of objects coincides in color and purpose. What should lie in the fourth pencil case, so that this pattern is preserved? (In each pencil case, there are exactly three objects: a pen, a pencil and an eraser.)
A square piece of paper is cut into 6 pieces, each of which is a convex polygon. 5 of the pieces are lost, leaving only one piece in the form of a regular octagon (see the drawing). Is it possible to reconstruct the original square using just this information?
Will the quotient or the remainder change if a divided number and the divisor are increased by 3 times?
Try to get one billion \(1000000000\) by multiplying two whole numbers, in each of which there cannot be a single zero.
Decipher the puzzle:
Decipher the puzzle: \(KIS + KSI = ISK\). The same letters correspond to the same numbers, different letters correspond to different numbers.
Ten people wanted to found a club. To do this, they need to collect a certain amount of entrance fees. If the organizers were five people more, then each of them would have to pay £100 less. How much money did each one pay?
Two tribes live on the island: natives and newcomers. It is known that the natives always tell the truth and the newcomers always lie. A traveler hired an indigenous islander as a guide. On the way, they met a man. The traveler asked the guide to find out which tribe this person belongs to. The guide returned and said that the man said that he was a native. Who was the guide – a native or a newcomer?
At the cat show, 10 male cats and 19 female cats sit in a row where next to each female cat sits a fatter male cat. Prove that next to each male cat is a female cat, which is thinner than it.