Jack and Ben had a bicycle on which they went to a neighborhood village. They rode it in turns, but whenever one rode, the other walked and did not run. They managed to arrive in the village at the same time and almost twice as fast than if they had both walked. How did they do it?
Three tourists must move from one bank of the river to another. At their disposal is an old boat, which can withstand a load of only 100 kg. The weight of one of the tourists is 45 kg, the second – 50 kg, the third – 80 kg. How should they act to move to the other side?
Try to decipher this excerpt from the book “Alice Through the Looking Glass”:
“Zkhq L xvh d zrug,” Kxpswb Gxpswb vdlg, lq udwkhu d vfruqixo wrqh, “lw phdqv mxvw zkdw L fkrrvh lw wr phdq – qhlwkhu pruh qru ohvv”.
The text is encrypted using the Caesar Cipher technique where each letter is replaced with a different letter a fixed number of places down in the alphabet. Note that the capital letters have not been removed from the encryption.
A kindergarten used cards for teaching children how to read: on some, the letter “MA” are written, on the rest – “DA”. Each child took three cards and began to compose words from them. It turned out that the word “MAMA” was created from the cards by 20 children, the word “DADA” by 30 children, and the word “MADA” by 40 children. How many children all had 3 of the same cards?
Try to make a square from a set of rods:
6 rods of length 1 cm, 3 rods of length 2 cm each, 6 rods of length 3 cm and 5 rods of length 4 cm. You are not able to break the rods or place them on top of one another.
Write a number instead of the space (in letters, not numbers!) to get a true sentence:
THIS SENTENCE HAS ... LETTERS
(Note that the dash does not count as a letter, i.e. the word twenty-two is made up of 9 letters).
Find the largest six-digit number, for which each digit, starting with the third, is equal to the sum of the two previous digits.
Find the largest number of which each digit, starting with the third, is equal to the sum of the two previous digits.
James spent the first Tuesday of some month in Liverpool and the first Tuesday after the first Monday he spent in Newcastle. In the next month, James spent the first Tuesday in Dover and the first Tuesday after the first Monday he spent in Bristol. Could you determine the dates (day and month) spent by James in each of the cities?
Dave spent the first Tuesday of the month in Bath, and the first Tuesday after the first Monday in Cardiff. The following month Dave spent the first Tuesday in London, and the first Tuesday after the first Monday in Cambridge. Can you determine what month and date Dave was in each of the cities?