At the tea party the Hatter, who loves everything being odd, decided to divide 25 cakes between himself, the March Hare, Alice, and the Dormouse in such a way that everybody receives an odd number of cakes. Show that he would never be able to do it.
Alice went to a shop to buy flowers for her sister. She bought 6 roses £1 each, 4 lilies 82p each, and 4 freesias 76p each. At the till she was asked to pay £12.25, which she asked to recalculate straight away pointing out that the amount was not correct. Alice did not calculate the full amount, but how did she know that they made a mistake?
The Hatter says that he knows four numbers such that their sum and their product are odd. Is he right? Can you expain why?
The four numbers 1, 1, 1, 2 are written on a piece of paper. Alice and the Hatter are playing a game. They add in turns 1 to any two numbers to make the new four numbers. The winner is the one to make all the four numbers equal. If Alice goes first, who will win, if any?
The Hatter is obsessed with odd numbers. He is very determined to represent 1 as \[1 = \frac{1}{a} + \frac{1}{b} + \frac{1}{c} + \frac{1}{d},\] where \(a\), \(b\), \(c\), and \(d\) are all odd.
Alice is very sceptical about it. Do you think you can help Alice to persuade the Hatter that it is impossible?
Prove that the equation \(x^2 + 4034 = y^2\) does not have solutions in integer numbers.
Find a solution of the equation \(x^2 + 2017 = y^2\) in integer numbers.
Alice marked several points on a line. Then she put more points – one point between each two adjacent points. Show that the total number of points on the line is always odd.
The date 21.02.2012 reads the same forwards and backwords (such numbers are called palindromes). Are there any more palindrome dates in the twenty first centuary?
Do there exist three natural numbers such that neither of them divide each other, but each number divides the product of the other two?